Rhubarb Crumble Frozen Custard
Happy Saturday, everyone! I can't tell you how grateful I am that it's finally the weekend, especially given the holiday. It means that for three days, I'll have my husband's company and his help watching our son. These past couple of weeks have been particularly difficult because our sweet, darling boy has abruptly entered his "picky-eater" stage. Cue ominous music. He used to eat everything we put in front of him. Eggs, pickles, collard greens, kimchi, whatever. But now all he wants is blueberries. And bacon. That's it. And if we attempt to feed him something else, he screams and throws everything on the floor. He doesn't do it at every meal, but when he does, it's... infuriating. I'll admit that I've lost my cool and have had to leave the room a few times. So last weekend when my husband realized that I was about to crack, he graciously let me spend both days working on a new recipe. Unfortunately, it ended up being a complete disaster. I was trying to rush through a rhubarb pastry because we're already halfway through the season, and the individual components were delicious. But the overall execution was a total mess. The textures were all wrong - chewy in the crispy places, runny in the creamy places, and monstrously over-proofed. So when confronted with weekend's worth of effort that I didn't want to go to waste, instead of letting this be one more failure in a long line of battles lost throughout the week, I chose to reimagine the ingredients. I was staring at a bowl of sweet vanilla pastry cream, tangy rhubarb compote, and stewed rhubarb when it hit me -
By combining the whole rhubarb pieces, tart jam filling, creamy custard, and a last-minute granola streusel for texture, my hodgepodge of ingredients turned into a fantastic frozen treat that tastes exactly like rhubarb crumble a la mode. From failure came sweet, sweet success.
For those of you who have never had frozen custard, it's basically really rich ice cream. The addition of eggs and flour makes for a creamier, denser product that doesn't have the tendency to get as icy as solely milk-based ice creams do. On the downside, it's not gluten-free. But it's rich, sweet, and perfectly balances the tartness of the rhubarb compote.
Full disclosure, this recipe works best if you have an ice cream maker. I was gifted one of Cuisinart's 1.5 quart machines several years ago, and this quantity fit inside it perfectly. But if you don't have one, you can still make a semifreddo, which translates to "half frozen" and is basically a frozen mousse with eggs. See the Notes for the alternate process.
This recipe is best tackled on and off over the course of a whole day or two. So if you're interested in making it for your Memorial Day cook-out, you'll want to buy the ingredients today and put the bowl of your ice cream maker in the freezer now. Don't stress; this recipe isn't too labor intensive. There are just several components that need to be chilled thoroughly before assembling and freezing the final mixture. You'll need to make a quick jam by simmering some chopped rhubarb, sugar, lemon juice, and water until thick and sticky, then chill. Meanwhile, gently stew the rest of the chopped rhubarb in a sugar syrup so that it softens while still retaining it's shape, and chill. Then mash together the ingredients for the streusel, bake, and chill. Finally, whip up the pastry cream in only a few minutes, then cover it and chill. Once everything has chilled for several hours, just combine the pastry cream, whipping cream, and some compote in the ice cream maker, and churn according to the machine's directions. Then layer each component in a lined loaf pan, swirl to distribute, and freeze until solid. Et voilá! That's all that stands between you and rich, tangy, homemade ice cream!
But even if you don't feel like making this treat, I hope you can appreciate it as a perfect example of taking failure and reimagining it into a totally unexpected success. Thanks for reading, and have a lovely long weekend!
Rhubarb Crumble Frozen Custard
Yields about 20 single scoop servings (one loaf pan)
550 g (1 1/4 lb) fresh rhubarb, trimmed & chopped
120 g (heaping 1/2 C) granulated sugar
40 g (3 T) fresh lemon juice (about one lemon)
40 g (3 T) water
300 g (about 12 oz) thin stalks of rhubarb, rough ends and leaves trimmed
130 g (2/3 C) granulated sugar
33 g (5 1/2 tsp) lemon juice
525 g (about 2 1/4 C) water
60 g (about 1/2 C) granola (any flavor)
60 g (1/2 C) all purpose flour
100 g (1/2 C) granulated sugar
1/4 tsp salt
70 g (5 T) unsalted butter, softened
Pastry Cream Base
500 ml (about 16 oz) whole milk
1 vanilla bean, scraped (or 1/4 tsp vanilla paste)
125 g (heaping 1/2 C) granulated sugar, divided in half
4 large egg yolks (about 74 g)
30 g (heaping 6 T) cornstarch
30 g (6 T) all-purpose flour
Plus: 230 g (1 C) heavy whipping cream
First and foremost, if you're using an ice cream maker, put the bowl of the machine in the freezer at least 24-48 hours before you want to churn your custard. If that's not possible, you could always fill the bowl with some dry ice and freeze it for about 12 hours or so. But that depends on the availability of dry ice in your area. You can also make a semifreddo instead (see Note 2).
Trim the rhubarb to remove any rough or split ends and leaves, then chop. Do not eat the leaves; they're toxic. Combine all of the ingredients into a saucepan, stir, and bring to a simmer over medium-high heat. Reduce the heat to medium and gently simmer for 10 minutes, stirring occasionally. Then simmer for another 5 minutes, stirring frequently to prevent sticking and burning. Once the mixture is thick and jammy, take it off the heat source and allow it to cool completely. Store it in the fridge in an air-tight container until thoroughly chilled, for up to 5 days (if you want to wait that long to assemble).
Cut a piece of parchment paper into a circle just large enough to fit inside a small pot; set aside. Chop the trimmed rhubarb into inch long pieces and set aside. Then mix the sugar, water, and lemon juice in the small pot and just bring it to a simmer over medium-low heat. Swirl to make sure all of the sugar has dissolved, then add the rhubarb. The syrup should barely cover the fruit. Bring it back to just a simmer, then immediately turn the heat to low. Cover the fruit with the parchment paper so that it remains submerged, and allow it to stew for 5 minutes. Then turn the heat off and let it cool for an hour. Finally, place the rhubarb and its syrup in a container and allow it to chill overnight in the fridge. It will allow the rhubarb to reach a softened, cooked texture while still holding it's shape. It may also be made a few days in advance.
Preheat the oven to 350°F. Meanwhile, stir together the granola, flour, sugar, and salt in a mixing bowl. Then cut in the butter using your fingers and massage it into the dry mixture until it is evenly distributed and resembles wet sand. Sprinkle the mixture onto a lined baking pan, and bake on the middle rack for about 20 minutes, stirring every 5 minutes, until golden brown. Set it aside to cool completely, then place it in a bag in the freezer until you're ready to assemble the ice cream. Any leftover streusel will last for up to a month in the freezer.
Pastry Cream Base
Mis en place is essential here because this process is lightening fast. First, weigh out your ingredients, combining the milk, scraped vanilla bean pod and seeds (or just vanilla paste), and half of the sugar in a heavy-bottomed saucepan. Until you're ready to begin, keep your egg yolks and the rest of the sugar separate because they react quickly when mixed. Also, make sure that your egg yolks are in a medium or large mixing bowl; you'll need space to whisk them vigorously. In a separate bowl, you may whisk together the flour and cornstarch, but don't add them to anything else until you're completely ready.
Now, place the milk mixture over medium heat and whisk to combine. While the milk is heating, whisk the egg yolks to loosen them. Then slowly pour the remaining sugar into the yolks while whisking vigorously until they become pale and ribbony (about 30 seconds). Next, add the flour and cornstarch and whisk gently until completely combined. Be sure to scrape the bowl well the incorporate all of the dry ingredients. The above should only take a minute or two, and keep an eye on your milk to make sure it doesn't quite reach boiling. If so, turn the heat down to low to keep it hot.
By now, your milk should be ready. While whisking continuously, slowly pour up to half of the milk mixture into your eggs. Pour the milk as a light, slow stream while mixing quickly so that the hot liquid doesn't scramble the eggs. Once half of the milk is in the eggs, return the pot to the stove and bring it back to a very gentle simmer over medium heat. Once simmering, turn the heat down to medium low and add the egg-milk mixture back into the pot, whisking in the pot as you go. Quickly scrape in as much of the egg as you can, then get back to whisking vigorously inside the pot, paying careful attention to the corners. It will only take 30 to 60 seconds for the cream to thicken to the point that it stands up like pudding. It should also burp a large bubble in the center if you were to stop whisking for a couple of seconds. Once either of these happens, immediately remove it from the stove and whisk it for a second just to pull it off of the bottom of the pan (see Note 1). Pour it into a shallow baking pan or bowl, smooth it down into a thin, even layer with a spatula, and press a sheet of plastic wrap over the surface to keep a skin from forming as it cools. Immediately place it in the fridge for several hours, until cold.
If you don't have an ice cream maker, see Note 2.
Once the bowl of the ice cream maker and each component has chilled thoroughly, line a loaf pan with plastic wrap or parchment paper, leaving lots of excess draped over the sides. Next, scrape the pastry cream into a mixing bowl, and whisk in the heavy cream and half of the rhubarb compote until blended. Pour the mixture into the bowl of the ice cream maker and churn according to the machine's instructions. For example, it took 20 minutes to thicken in my 1.5 quart machine. Next, scrape about a third of the thickened custard into the lined pan. Spoon a third of the remaining compote on top, followed by a handful of the streusel, and a third of the stewed rhubarb (discarding the syrup), then swirl with a spatula to distribute. Repeat twice more with the remaining ingredients. Press plastic wrap against the surface of the custard so that it doesn't get icy, and freeze for at least 4 hours.
- If the pastry cream looks like it has started to curdle, you can save it by straining it through a fine mesh sieve before pouring it into the pan to cool. Press the curds through the sieve with a spatula to break them up. But if your pastry cream has totally broken, you'll have to start again.
- For a semifreddo, instead of slowly churning air into the custard mixture, you'll have to whip the heavy cream by itself to soft peaks. Separately, whisk together half of the compote mixture into the pastry cream. Then gently fold the whipped cream into the pastry cream, and fill the lined loaf pan as instructed above, including the extra toppings. Once frozen, instead of scooping out the dessert, remove the whole brick from the pan and slice to serve. Enjoy!