Raspberry Ripple with Oat Crunch Ice Cream

Prepare crumble: Preheat oven to 350°. Place brown sugar, flour, butter, rolled oats, cinnamon, baking powder and 1/4 teaspoon salt in the bowl of a food processor. Pulse until mixture begins to clump together and oats are finely chopped. Transfer to a small baking sheet lined with parchment paper. Press evenly over sheet; mixture will remain somewhat crumby in texture. Freeze until firm, about 10 minutes.

Transfer to oven and bake until golden and crisp, 15 to 20 minutes, stirring once or twice to bake evenly. Cool completely on a wire rack. Crumble cooled mixture with your hands. (Mixture can be stored in an airtight container up to 5 days before using.)

Prepare ice cream: Place raspberries, 1/4 cup granulated sugar and 1/4 cup water in a food processor. Puree and strain. You should have about 11/2 cups. Remove 3/4 cup puree and set aside. Pour remaining puree into a small saucepan. Bring to a simmer over medium heat and cook until thick and jammy, 7 to 9 minutes. Let cool completely.

In a large saucepan, combine milk, cream, the remaining 3/4 cup sugar and 1/8 teaspoon salt. Bring just to a simmer over medium heat, stirring until sugar is dissolved. Remove from heat.

Place cream cheese and cornstarch in two separate small bowls. Ladle 1/4 cup milk mixture into each bowl. Whisk each until smooth. Pour cornstarch mixture into remaining milk mixture in saucepan and return to medium heat. Bring just to a boil, then cook and stir until slightly thickened, 2 to 3 minutes. Remove pan from heat; whisk in cream cheese mixture and vanilla, followed by reserved 3/4 cup raspberry puree. Transfer mixture to a large bowl and refrigerate, covered, at least 4 hours.

Transfer mixture to an ice cream maker and freeze according to manufacturer's instructions. Fold in 2 cups crumble. Transfer half the ice cream to a 2-quart container, drizzle with half the raspberry sauce, then repeat layers. Gently swirl with a butter knife. Top with any remaining crumble, cover tightly and freeze until firm. Store up to 3 months.