Raspberry and Blueberry Cobbler

1 . Stage

Preheat oven to 400 degrees F (200 degrees C). Line a baking sheet with aluminum foil.

2 . Stage

Mix flour, 1/2 cup sugar, baking powder, and salt in a bowl; mash butter into the flour mixture until crumbly. Stir boiling water into the flour mixture to form a dough.

3 . Stage

Dissolve cornstarch in cold water in a separate large bowl. Stir blueberries, raspberries, 3/4 cup sugar, and lemon juice into the cornstarch mixture; transfer to a cast-iron skillet and bring to a boil, stirring frequently. Drop dough into the skillet by the spoonful. Put skillet onto the prepared baking sheet.

4 . Stage

Bake in preheated oven until the topping is golden brown, about 25 minutes.