To make this ice cream, perfected by Jane Nguyen, our production coordinator, we pushed the boundaries of butterfat, creating a super-high-fat base in order to compensate for blueberries’ water content. We make a blueberry compote and then swirl it throughout the base for a gorgeous uniform color. Cooking the blueberries helps get rid of some water, which ensures that the ice cream won’t be icy. When frozen, water crystallizes, which can form pockets of ice within ice cream (never a good sign). If you want to get really geeky about it, here’s something to think about: Prime time for berry picking is after a few dry days; after it rains, berries tend to take on a lot of water, which can dilute their flavor. Out of season, frozen tiny wild Maine blueberries are a great choice, as they are readily available nationally and year-round, but they might require slightly longer cooking time, as frozen berries contain moisture from ice crystals.
MAKES ABOUT 1 QUART
FOR THE BLUEBERRY COMPOTE
1 pint blueberries
¼ cup (50 grams) sugar
2 tablespoons fresh lemon juice
½ teaspoon finely grated lemon zest
FOR THE ICE CREAM BASE
2½ cups heavy cream
½ cup whole milk
¾ cup plus 2 tablespoons (175 grams) sugar
¼ teaspoon (1 gram) kosher salt
8 large egg yolks
1. To make the blueberry compote, combine the blueberries, sugar, lemon juice, lemon zest, and ⅔ cup water in a saucepan. Heat over medium-low heat until jamlike and syrupy, about 10 minutes. Remove from the heat and set aside to cool.
2. To make the blueberry ice cream, pour the cream and milk into a double boiler or a heatproof bowl set over a saucepan of gently simmering water (the bottom of the bowl should not touch the water). Whisk in ½ cup (100 grams) of the sugar and the salt and stir until they have dissolved. Warm the mixture until you see steam rising from the top.
3. Meanwhile, prepare an ice bath in a large bowl and set another bowl over it. Set aside.
4. In a medium bowl, with a kitchen towel underneath it to prevent slipping, whisk together the egg yolks with the remaining 6 tablespoons (75 grams) sugar until uniform. While whisking, add a splash of the hot dairy mixture to the yolks. Continue to add the dairy mixture, whisking it in bit by bit, until you’ve added about half. Add the yolk mixture to the remaining dairy mixture in the double boiler. Set the heat under the double boiler to medium and cook the custard, stirring continuously with a wooden spoon and reducing the heat to medium-low as necessary, until steam begins to rise from the surface and the custard thickens enough to coat the back of the spoon. Hold the spoon horizontally and run your finger through the custard. If the trail left by your finger stays separated, the custard is ready to be cooled.
5. Strain the custard into the bowl sitting over the prepared ice bath and stir in 2 cups of the blueberry compote (reserve any remaining blueberry compote for another use—it will keep in an airtight container in the refrigerator for up to 2 weeks). Stir for 3 to 5 minutes, or until the custard has cooled. Transfer the custard to a quart-size container, cover, and refrigerate for at least 4 hours or, preferably, overnight.
6. Pour the chilled custard into an ice cream maker and freeze according to the manufacturer’s instructions. Place the container in which you refrigerated the custard in the freezer so you can use it to store the finished ice cream. Churn the ice cream until the texture resembles “soft serve.” Transfer the ice cream to the chilled storage container and freeze until hardened to your desired consistency. Alternatively, you can serve it immediately—it will be the consistency of gelato. The ice cream will keep, frozen, for up to 7 days.