Rhubarb-Apple Almond Cobbler
1 1/2 pounds rhubarb, cut into 1-inch pieces (about 5 cups)
2 tart apples, such as Granny Smith (1 pound total), peeled, cored, and cut into 1/2-inch pieces (2 1/2 cups)
1 1/2 cups granulated sugar
3 tablespoons cornstarch
1/2 teaspoon grated fresh ginger
2 teaspoons fresh lemon juice
1/2 teaspoon kosher salt
1 1/2 cups unbleached all-purpose flour
1/4 cup finely ground almond flour
1/4 cup granulated sugar
1 3/4 teaspoons baking powder
3/4 teaspoon kosher salt (we use Diamond Crystal)
6 tablespoons cold unsalted butter, cut into pieces
3/4 cup heavy cream, plus more for brushing and serving
1/4 teaspoon pure almond extract (optional)
Sliced almonds and fine sanding sugar, for sprinkling (optional)
Filling: Preheat oven to 375°F. In a large bowl, combine rhubarb, apples, granulated sugar, cornstarch, ginger, lemon juice, and salt. Transfer to a 2 1/2-to-3-quart baking dish or 9-by-13-inch baking pan.
Biscuit: Whisk together both flours, granulated sugar, baking powder, and salt. Add butter; using your fingers, work it into dry ingredients until largest pieces are the size of small peas. Add cream and almond extract; stir with a fork until a soft, sticky dough forms. Scatter in small clumps evenly over fruit in baking dish. Brush dough with cream. Sprinkle with almonds, then sanding sugar.
Bake until cobbler is bubbling in center and biscuits are golden brown, 55 to 60 minutes (if browning too quickly, tent with foil after about 45 minutes). Let cool on a wire rack at least 1 hour before serving warm or at room temperature, topped with more cream.