- 1 1/2 pounds rhubarb, cut into 1/2″ pieces
- 1/3 cup dry red wine
- 1/3 cup granulated sugar
- 1/2 teaspoon kosher salt
- 1/2 vanilla bean, halved lengthwise
- 1 1/4 cups all-purpose flour
- 1/3 cup chopped macadamia nuts
- 1/3 cup granulated sugar
- 1 teaspoon kosher salt
- 1/2 teaspoon vanilla extract
- 1/2 cup (1 stick) chilled unsalted butter, cut into pieces
- 2/3 cup chilled heavy cream
- 1 tablespoon powdered sugar
- 1 pint vanilla ice cream
- 1 pint lemon ice cream or sorbet
- Preheat oven to 350°. Combine rhubarb, wine, granulated sugar, and salt in an 8×8″ baking dish, scrape in seeds from vanilla bean, and toss to combine; discard pod. Roast, tossing halfway through, until rhubarb is very tender but not falling apart, 25–30 minutes; let cool.
- Combine flour, macadamia nuts, granulated sugar, salt, and vanilla in a medium bowl.
- Using your fingers, work butter into flour mixture until mixture holds together when squeezed. Break up into small clumps and scatter onto a rimmed baking sheet. Bake, tossing halfway through, until crumble is golden brown, 15–20 minutes. Let cool.
- Beat cream in a small bowl to soft peaks and whisk in powdered sugar.
- Scoop vanilla and lemon ice cream into glasses and top with roasted rhubarb, whipped cream, and crumble.