Preheat the oven to 350°F and line an 8x8 baking pan with parchment paper (or coat with nonstick spray).
Halve peaches and remove pit, then slice or cut into chunks (peeling isn’t necessary).
1/2 pound peaches
Toss in a bowl with 1 tablespoon brown sugar and set aside.
1 tablespoon brown sugar
In a large bowl, combine flour, granulated sugar, baking powder, salt, and cinnamon.
1 cup all-purpose flour, 1/3 cup granulated sugar, 2 teaspoons baking powder, 1/2 teaspoon fine sea salt, 1/4 teaspoon ground cinnamon
Whisk together egg and milk, then pour into dry mixture and stir until well combined.
1 egg, 1/2 cup cold milk
Add peaches, leaving excess liquid behind, and fold to combine into batter. Pour into prepared pan.
To make the topping, in a small bowl, combine flour, brown sugar, granulated sugar, and salt. Cut in butter with a pastry blender or two knives until mixture forms small chunks and looks a bit like clumpy wet sand. Scatter over the top of the batter in the pan.
1/3 cup all-purpose flour, 2 tablespoons brown sugar, 2 tablespoons granulated sugar, Pinch fine sea salt, 2 tablespoons cold butter
Bake for 30-40 minutes, until browned and a toothpick inserted in the center comes out clean.