Makes 1 liter of frozen custard; 1 hour 30 minutes active, 3 hours 30 minutes to 16 hour totalIngredients:
Ice, for two ice baths, as needed
275 grams granulated sugar
100 grams water, for caramel
650 grams milk, whole
150 grams heavy cream
45 grams nonfat dry milk powder
10 grams vanilla extract
5 grams salt
200 grams egg yolk
About 1 kilogram dry ice, as needed
Equipment:
Sous vide setup or Joule
Whisk
Fine-mesh sieve
Ziplock-style bag (1 gallon)
Stand mixer with paddle attachment
Directions:
One great thing about cooking your custard base sous vide is that you can precisely control the flavor and texture of the finished product. We loved the clean, creamy flavor of custard cooked at 149 °F / 65 °C, but the super-eggy flavor we got at 176 °F / 80 °Creminded us of the frozen treats we get at our favorite place in Seattle, Old School Frozen Custard. Pick your favorite temp—or experiment with both!—then preheat Joule and start making your base. For a creamy but not eggy custard, you'll want to cook the custard base at 149 °F / 65 °C. For a super-creamy, eggy custard, preheat to 176 °F / 80 °C instead.
Set up an ice bath near your workstation. Fill a large bowl with lukewarm water. Set aside. Pour sugar into a pot, and cover with 100 g of water. Make sure all the sugar is covered—check for stragglers on the sides of the pan. Place pot over medium-high heat. Allow the sugar to cook, undisturbed, to 385 °F / 196 °C. (Stirring or agitating the pot can cause the sugar to crystallize. We don't want that.) While caramel cooks, combine milk and cream in a separate pot. Add nonfat dry milk powder, vanilla, and salt, and whisk until all the powders are dissolved. Begin heating on medium. Remove the caramel from the heat, and place it atop the bowl of lukewarm water to cool it down a little. Don't be alarmed if the caramel spits at this point, but do watch out for your poor arms and hands.
Keep cooking milk and cream until you see a little bit of steam rising and the liquid is warm to the touch. Add caramel to the cream mixture, whisking constantly to combine. The caramel might start to harden and stick to the whisk and the sides of the pan. Keep whisking to break it down. Once all the hard caramel has been dissolved into the liquid, remove from heat. Strain through a fine-mesh sieve into a bowl, and cool it down a bit in the ice bath.
Add the egg yolks and whisk until well combined.
Transfer mixture to a bag or glass jar and cook for 60 minutes, agitating every 10 minutes to ensure even cooking. Remember, 149 °F / 65 °C yields creamy custard with a clean flavor. Custard cooked at 176 °F / 80 °C will turn out even creamier, with a nice and eggy flavor. Either way, the cook time remains the same, but if you're cooking at the higher temp, opt for a glass jar or heavy-duty sous vide bag to reduce the chance of leaks.
Make up an ice bath. Once custard is finished cooking, transfer to the ice bath to cool.
Now put that bag of custard in the fridge for at least four hours or as long as overnight. This step is optional, but it leads to smoother, more scoopable frozen custard.
Carefully transfer your dry ice to a burlap sack, a clean tote bag, or even a bath towel, and wrap it up completely so you won't burn yourself. With a heavy cast iron pan or a hammer, crush dry ice into a fine powder. Transfer crushed dry ice to a plastic bowl or Tupperware container.
Pour your custard base into the bowl of a stand mixer fitted with the paddle attachment, and begin mixing on low. Add dry ice one spoonful at a time. Allow foam and steam to dissipate, then add another spoonful. Keep adding spoonfuls of dry ice until the custard base begins to thicken. When it does, increase mixing speed, continuing to add spoonfuls of dry ice until your custard is rich, thick, and creamy. (You may need less than 1 kg or slightly more; it depends on many different factors. So just go slow and eyeball it—when your base starts to look like frozen custard, it probably is!) When custard looks ready, continue mixing for a minute or two to make sure you break up any chunks of dry ice.
The custard is ready to eat immediately, but we like to let it harden in the freezer for a couple hours so it doesn't drip all over the damn place.
ChefSteps comprises a team of award-winning chefs, filmmakers, scientists, designers and engineers focused on revolutionizing the way people cook by inspiring creativity and encouraging expertise in the kitchen. Try your hand at sous-vide cooking with the Joule, specifically designed to bring elevated cooking to your fingertips.
