Ingredients
3/4 cup granulated sugar
1/4 cup cornstarch
1/2 teaspoon kosher salt
2 pounds blueberries (6 cups)
1 tablespoon fresh lemon juice (from 1/2 lemon)
6 tablespoons unsalted butter, room temperature
1/4 cup light-brown sugar
1 cup unbleached all-purpose flour, spooned and leveled
1/2 teaspoon kosher salt
Vanilla ice cream, for serving (optional)
Preparation
Filling: Preheat oven to 375 degrees. In a large bowl, whisk together granulated sugar, cornstarch, and salt. Fold in blueberries and lemon juice until well coated. Transfer to an 8-inch square baking dish.
Topping: In the bowl of a stand mixer fitted with the paddle attachment, beat together butter and brown sugar on medium speed until light and fluffy. Add flour and salt; using your hands, mix until large pieces form. Scatter evenly over filling.
Bake until center is bubbling, 55 minutes to 1 hour, tenting loosely with foil after 30 minutes. Let cool at least 30 minutes before serving, with vanilla ice cream if desired.
