Recipe and photos by Brandon Matzek
With its crisp, cinnamon-spiked oat crumble and spheres of purple-tinged ice cream, this seasonal dessert is the perfect ending to any hot summer day. Blueberry Ice Cream with Oat Crumble Topping starts with a base of simmered fresh blueberries flavored with lemon juice and sugar. The cooking process draws out some of the moisture while concentrating the blueberry flavor. After a quick strain, the resulting liquid, stained a deep shade of blue-purple, captures the pure essence of blueberry.
This flavor bomb is mixed into a French custard base, and then churned into a cold, creamy confection. A final sprinkling of crunchy oat crumbles provides a satisfying contrast in both flavor and texture.
Making ice cream at home is easy to do, but you will need some special equipment (ice cream maker, fine-mesh strainer, plenty of bowls) and a little advanced planning. Start by preparing your ice cream base a day in advance. Letting the ice cream base chill overnight will help you achieve a perfectly creamy texture. You can also make the crumble topping a day in advance. Store in an airtight container until you are ready to serve.
Blueberry Ice Cream with Oat Crumble Topping
For the ice cream:
4 cups fresh blueberries
1/4 cup plus 1 cup sugar
Juice of 1/2 lemon
1 1/2 cups heavy cream
1 1/2 cups half-and-half
5 large egg yolks
For the oat crumble topping:
3/4 cup flour
1/4 cup plus 1 1/2 tablespoons packed light brown sugar
1/2 tsp. kosher salt
1/8 tsp. ground cinnamon
1/4 lbs. (1 stick) unsalted butter, cut into 1/2-inch cubes and chilled
3/4 cup old-fashioned oats (not quick or instant cooking)
Flavor foundation. Place blueberries, 1/4 cup sugar and lemon juice in a medium saucepan. Cook over low heat, stirring occasionally, until the blueberries release their juices and begin to cook down (about 20 minutes). You can help this process along a bit by gently mashing the berries each time you stir. Drain blueberry juice into a clean bowl using a fine mesh basket strainer, pressing berries to squeeze out as much liquid as possible. Set aside.
Be prepared. Prepare an ice bath in a large bowl and have another strainer ready. Add heavy cream to a medium-sized bowl and set aside.
Custard base. Heat half-and-half and 1 cup sugar in a different saucepan over low heat, stirring to dissolve the sugar. Remove from heat when steam rises from the surface and the mixture is completely heated through. Meanwhile, whisk 5 egg yolks in a bowl until slightly thickened. Slowly, while whisking, add 1/2 cup of the warm half-and-half mixture to the yolks. Once the 1/2 cup is incorporated, whisk in the remaining half-and-half mixture. Return the half-and-half/yolk mixture to the saucepan, and cook over medium heat, stirring constantly with a wooden spoon. The custard is thick enough when steam rises from its surface and the custard coats the spoon. Strain the custard into the bowl with the heavy cream. Stir to combine.
Blend and freeze. Add the blueberry juice to the custard mixture and stir. Place the bowl in the ice bath and stir occasionally to cool (be sure not to get any water in the custard mixture). Refrigerate until cold (at least 4 hours, but better overnight). Freeze custard in an ice cream maker according to the manufacturer's instructions. Transfer to an airtight container and chill in the freezer for 2 to 3 hours before serving.
Crumble and bake. Preheat an oven to 350°F and place a rack in the center of the oven. Add flour, brown sugar, cinnamon and salt to a medium bowl, stirring to combine. Using your hands, quickly work the butter into the flour-sugar mixture. Continue pressing the butter into the dry ingredients until the mixture resembles wet sand. Stir in the oats, then transfer the entire mixture to a rimmed baking sheet. Break up any clumps that are larger than 1/2-inch. Bake until the mixture turns golden brown and crisp (30 - 35 minutes), stirring every 10 minutes to ensure even cooking. Let cool before sprinkling over the blueberry ice cream.