Step 1

Arrange a rack in the middle of the oven and heat the oven to 375°F. Coat a 2-quart or 11x7-inch baking dish with butter.

Step 2

Make the crumble topping: Cut 1 stick unsalted butter into 8 pieces and place in a medium microwave-safe bowl. Microwave until mostly melted, 40 to 50 seconds. (Alternatively, melt the butter in a small saucepan over medium heat and pour into a medium bowl.)

Step 3

Add 1 cup all-purpose flour or gluten-free all-purpose flour blend, 1/2 cup packed light brown sugar, 2 teaspoons vanilla extract, 1 teaspoon kosher salt, 1 teaspoon baking powder, and 1 teaspoon ground ginger, and stir to combine. The mixture will be thick and crumbly. Refrigerate for at least 5 minutes or until ready to use.

Step 4

Make the filling: Halve and pit 2 pounds peaches (no need to peel). Cut into 1/2-inch thick slices. Place the peaches, 1/4 cup packed light brown sugar, 2 tablespoons cornstarch, 1 teaspoon kosher salt, and 1 teaspoon vanilla extract in a large bowl.

Step 5

Finely grate the zest from 1/2 medium lemon into the bowl. Juice the lemon half until you have 1 tablespoon juice, then add to the bowl. Stir to combine.

Step 6

Transfer the peach filling to the baking dish and spread into an even layer. Break the crumble topping into large clumps with your hands and scatter over the filling in an even layer.

Step 7

Bake until the crumble topping is golden-brown and the filling is bubbling, 35 to 40 minutes. Let cool for at least 15 minutes before serving with vanilla ice cream if desired.