Ingredients
1 cup (2 sticks) unsalted butter, cold, cut into small pieces, plus more for baking dish
2 1/4 cups all-purpose flour
3/4 cup packed dark-brown sugar
1/3 cup plus 1/2 cup granulated sugar
1/2 teaspoon ground cinnamon
1/4 teaspoon mace
1/2 teaspoon salt
1/2 cup old-fashioned rolled oats
2 cups blueberries
3 pounds apples (about 8), peeled, cored, and cut into thin wedges
Juice of 1/2 lemon (about 1 tablespoon)
2 tablespoons flour
Vanilla ice cream or whipped cream, for serving (optional)
Preparation
Preheat oven to 375 degrees, with a rack in the lower third. Butter a 3-quart baking dish, and place on a parchment-lined baking sheet; set aside.
In a large bowl, whisk together flour, brown sugar, 1/3 cup granulated sugar, cinnamon, mace, and 1/4 teaspoon salt. Using a pastry blender, cut in butter until large clumps form. Using a rubber spatula, mix in oats. Set aside.
In a large bowl, toss together blueberries, apples, lemon juice, remaining 1/2 cup granulated sugar, flour, and remaining 1/4 teaspoon salt to combine. Pour the blueberry and apple mixture into the prepared baking dish; sprinkle with reserved oat mixture, covering fruit evenly. Bake until juices are bubbling and the topping is evenly browned, about 50 minutes. Cool slightly on a wire rack. Serve crisp warm, topped with vanilla ice cream or whipped cream, if desired.
