French Chocolate + Grapefruit Mousse Pots

French Chocolate + Grapefruit Mousse Pots

Ah, tedium.  Aside from very tasty, tedious is exactly how I'd describe these little jars.  I love the complexity of multi-layered desserts that marry different textures, flavors, and methods.  But I'm surprised at how I managed to roll up so many into only 7 tiny ounces.

Instead of the effort it takes to make these, I should probably focus on how delicious they are.  How rich and intense the chocolate mousse is.  Or how bright and tangy the grapefruit cream is.  Or how nice the play of textures is between the smooth fillings, springy sponge cake, crunchy chocolate streusel, and chewy candied grapefruit rind.  They really are delicious; there are just a few steps involved.

Semisweet chocolate and grapefruit pair really well together.  But the beauty of this recipe is that it's highly adaptable.  You can switch out grapefruit for any citrus, or use concentrated tea or espresso instead.  You can even nix the additional flavoring all together and make plain chocolate mousse and vanilla cremeux.  And each step will familiarize you with several different techniques - candying citrus, creating streusels (great baked onto fruit pies and coffee cakes), and making traditional French chocolate mousse, cremeux (kind of a "creamy" pudding), and joconde (a whole-egg sponge cake).

If you don't want to make all five different recipes for such a small yield, I totally get it.  But the workload is the same if you'd like to double the recipe.  Or, you could even just make one part for a totally different use!  The chocolate mousse on it's own is incredibly rich and surprisingly airy given that there's no whipped cream involved.  And the joconde is perfect for jelly rolls and bûche de noël.  

I adapted the individual portions of this recipe from other sources to fit my needs, and you could either use mine or check out the originals (listed below).  Whichever you choose, I hope you enjoy the process and learn something new.  The reward is very tasty if you're up for the challenge!

French Chocolate + Grapefruit Mousse Pots

This recipe is best tackled over the course of several days.  The first three components are not too time consuming, but done all at once, the whole recipe is admittedly very tedious.

Yields: 6 servings (I used Weck 7.4 oz Tulip Jars)

Ingredients

Chocolate Grapefruit Streusel (Garnish - Modified from Chef Eddy)
56.5 g (4 T) unsalted butter, cold & cut into small cubes
1/2 tsp vanilla extract
1 g (1 tsp) grapefruit zest
50 g brown sugar
71 g all-purpose flour
4 g (1 T) dark cocoa powder

Candied Grapefruit (Garnish)
1 grapefruit
240 g sugar
237 ml (8 fl. oz) water

Grapefruit Almond Joconde (Modified from Joe Pastry)
28.5 g (2 T) butter (will reduce to 20 g when clarified)
3 large egg whites, room temperature
12 g granulated sugar
112 g finely ground almonds
114 g powdered sugar
3 large whole eggs, room temperature
6 g grapefruit zest (from about 1/2 grapefruit)
70 g all purpose flour

Chocolate Grapefruit Mousse (Modified from Kitchy Kitchen)
57 g semisweet chocolate (60% cocoa)
57 g unsalted butter
20 ml (4 tsp) fresh grapefruit juice, separated into 15 ml (3 tsp) and 5 ml (1 tsp)
24 g egg yolks (from a little less than two yolks - See Note 1)
40 g plus 2 g sugar, separated
1/4 tsp vanilla extract
1 tsp (5 ml) dark rum
40 g egg whites (from a little less than two whites - See Note 1), room temperature
pinch of salt
1/8 tsp cream of tartar

Grapefruit Cremeux (Modified from Chef Eddy)
4 large egg yolks
180 g granulated sugar
6 g grapefruit zest (from about 1/2 grapefruit)
207 ml (7 fl. oz) fresh grapefruit juice
118 ml (4 fl. oz) heavy cream
3 g powdered gelatin (about 1/2 of one envelope)
60 ml (4 T) ice cold water

Directions

Streusel
Preheat the oven to 350°F and set a rack in the middle.

In a mixing bowl, combine all of the ingredients using your fingers to blend-in the butter until no obvious pieces remain.  Crumble the mixture into a sheet pan (no lining required), and bake until dry and pebbly - about 15 minutes.  Remove from the oven and allow to cool completely, then store in an airtight container for up to a week.  The mixture can be made weeks in advance and stored unbaked in the freezer, as well.

Candied Grapefruit
Cut a piece of parchment paper to fit the inside of a small pot.  Set aside.

Using a channel knife (like this - video), peel off strips of grapefruit skin (making zigzag or spiraled patterns if desired).  You can also just use a pairing knife to cut thin strips instead; just don't take off any of the bitter white pith along with it.  Remove as much zest as possible.  You can snack on any extra that won't fit into the finished mousse pots.

Place the sugar and water in the pot and bring to a boil.  Reduce to barely a simmer, add the peels, and cover with the parchment paper so that the peels remain submerged.  Simmer for an hour, until translucent.  Remove and place on a cooling rack over a sheet pan (to catch drips).  Allow them to dry completely, at least several hours.  Store in an air tight container for up to a week.

Grapefruit Almond Joconde Cake
Place the butter in a small sauce pan and allow it to melt over medium heat.  Once it begins to simmer and foam, reduce the heat to medium-low and skim off the foam and floating solids.  Continue to skim it until it is clear.  Weigh the now clarified butter; it should be 20 grams.  If not, make a little more, then set aside.

Preheat the oven to 425°F and set a rack in the middle.

Cut two pieces of parchment to exactly fit the inside of a rimmed half-sheet pan or an 18x13 inch rectangular cheesecake pan (like this).  Dab some melted butter (NOT your clarified butter) onto the bottom corners of one sheet of parchment to adhere it to the pan, then brush the entire top of the same sheet with more melted butter.  Set the pan and the second, loose sheet of parchment aside.

In the bowl of a stand mixer fitted with a whisk, whip the egg whites to soft peaks, add the sugar, and continue to whip to stiff peaks. Scrape the meringue into a clean bowl.

Wash the bowl of the mixer and dry it, then switch to the paddle attachment. Beat the ground almonds, powdered sugar, whole eggs, and grapefruit zest on medium until they’re light and increased in volume, about 3 full minutes. Turn the mixer down to very low and add the flour, stirring just until it disappears.

Remove the bowl from the mixer and gently fold in the meringue. Lastly, fold in the clarified butter.
Pour the batter into your parchment-lined sheet pan, using a large offset spatula to spread it into the corners and smooth it out as evenly as possible.

Bake for 7 minutes, or until the cake is slightly springy and lightly browned. Remove from the oven and place the pan on the stove top. Cover it with your second sheet of parchment, then flip the pan over onto the countertop, which should pop the cake out of the pan. Carefully peel off the buttered layer of parchment, lay a cooling rack upside-down on top of the cake, flip it back over, and remove the second piece of parchment paper.  Allow it to cool completely.

Once cool, gently (but securely) wrap the cake in plastic wrap, then lay it flat in the freezer to harden for a couple of hours.  You can place it (wrapped in plastic) back in the sheet pan or on a the cooling rack so that it doesn’t fall apart in the freezer.  Keep the sponge cake in the freezer until you’re ready to assemble your final dessert, up to a week.

Mousse
First, prep ALL of your cremeux and mousse ingredients.  This is crucial.  Place ingredients from similar steps near each other, and even label them with tape, if necessary.  Without proper miss en place, the sheer number of ingredients used during these next two stages will have you pulling your hair out.  There are also several time-sensitive steps, so you can’t stop half way to measure a missing ingredient.

Make an ice bath and set it aside.

Fill the base of a double boiler or a small sauce pan halfway with water.  Place over high heat, then rest the top half of the double boiler or a mixing bowl on top.  Be sure that the water does not touch the base of the bowl.

Bring the water to a boil, then place the chocolate, butter, and 15 ml (3 tsp) of grapefruit juice in the overlying bowl.  Gently stir it with a spatula as it melts, until it is well combined and smooth.

Remove the top pan or bowl from the heat.  Either pour the chocolate mixture into another bowl and clean the double boiler, or retrieve a second bowl and place it on top of the boiling water.  Set the chocolate mixture aside.

Add the egg yolks, 40 g of sugar, remaining 5 ml (1 tsp) of grapefruit juice, vanilla extract, and rum to the clean bowl.  Whisk over boiling water for approximately 5 minutes, until the mixture is thick, opaque, and pale, similar to runny pudding.  Remove from heat and place it in ice bath.  Be sure that no ice water spills into the egg yolk mixture.  Continue to whisk the mixture until it cools and thickens significantly, approximately 5 minutes.  Thick ribbons of custard should fall from the lifted whisk once thick enough.  Once cool and thick enough, gradually pour the chocolate mixture into it, stirring constantly.  If you add the warm chocolate too quickly, you may nearly scramble the eggs.  Stir until smooth, then set aside.

Set the ice bath aside for later when you make the cremeux.

Pour the egg whites, salt, and cream of tartar into a very clean and dry bowl and whisk rapidly until frothy.  This can either be done manually or with a stand mixer.  Add the remaining 2 g of sugar and whisk until shiny, soft peaks form.  Gently fold a third of the meringue into the chocolate mixture.  Fold the second third into the chocolate mixture, then the final third until just barely combined (no streaks remain).  If you fold or stir too much, you'll break the air bubbles in the egg white mixture and the mousse will fall flat.

Pour the mousse into a second piping (or plastic) bag, set it upright in a glass, and place it in the refrigerator to firm up a bit while you make the creme.

Cremeux
Replenish the ice bath with more ice, and set it close-by.

In a small bowl, whisk together the egg yolks for 30 seconds.  Set aside.

In a non reactive saucepan (stainless steel or enameled), whisk together the sugar, grapefruit zest, grapefruit juice, and heavy cream. Over medium-high heat, bring the mixture to a boil, then immediately remove it from the heat.

Very slowly, pour the grapefruit mixture in a thin stream into the egg yolks while whisking rapidly.  Continue to whisk and slowly pour in the mixture until all of it has been added.  Doing so too quickly will scramble your egg yolks.  Once combined, pour the entire mixture back into the sauce pan and heat on medium while whisking constantly until the mixture reaches 185°F (83°C) on a candy or digital instant-read thermometer. Remove from heat.

In a small bowl, sprinkle the gelatin into the ice cold water, stir to moisten, and allow it to sit for 5 minutes to bloom. Then pour it into the cream mixture and whisk until melted.  Place the sauce pan inside the ice bath (making sure that no water falls into the mixture) and whisk until the mixture cools to room temperature.  Strain it through a fine mesh sieve into an uncut piping (or plastic) bag, sit it upright in a glass, and place it in the refrigerator to firm up for 30 minutes.

Assembly
While the mousse and cremeux are chilling, remove your sponge cake from the freezer and unwrap it.  Using sharp biscuit cutters (like these), cut the cake into 24 rounds - 4 different layers for each of the 6 jars.  Be sure that the size cutters you use is just smaller than the diameter of the jars.  If you're using Weck's tulip jars like I did, some layers will need to be smaller than others since the jars are bell-shaped.  A 2.75 inch (70 mm) round cutter will fit the widest section, and a 2.25 inch (57 mm) cutter will fit the narrowest.  Cut out the 24 layers, then allow them to come to room temperature.  You’ll have to bend them to fit through the narrow opening of the jar, so they’ll need to be relatively warm and flexible.

After the cremeux has chilled for 30 minutes, remove it and the mousse from the refrigerator.  Cut open the piping bags (or cut a small corner off of the plastic bags) and stand them upright inside their glasses so that the fillings don’t ooze out.  Gather your chocolate streusel as well.

If necessary, recut 6 of the cake rounds to be as wide as the bottom of the jars.  Place these rounds in the jars, being careful not to crack them when squeezing through the jar opening.

Pipe a 1/4 to 1/2 inch layer of chocolate mousse on top and spread it using a spoon to cover the sponge cake.  Sprinkle it with some streusel.  Place another sponge round, cut to fit if necessary, on top of the mousse in each jar.  Pipe a similar layer of grapefruit cremeux on top, spread it evenly, then cover with another piece of sponge cake.  Continue to alternate with one more layer of mousse, steusel, one more layer of cake, and one more layer of cremeux.  Cover the jars with their lids or plastic wrap and chill for at least 4 hours (preferably overnight) until firm.

When ready to serve, garnish the mousse pots with your remaining streusel and candied grapefruit.  Enjoy for up to 4 days!

Notes

  1. For the chocolate mousse, the egg white and yolk measurements have been listed by weight, in grams.  This is because the recipe calls for less than 2 whole eggs.  You're welcome to double the mousse recipe in order to avoid fractioning your eggs, but you'll end up with a LOT of extra.  Pour the excess into ramekins or small glasses to serve on its own if you'd like.
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