Step 1

For the apples: Preheat the oven to 350 degrees F. Grease a 9-by-13-inch glass baking dish with butter.

Step 2

Arrange the apple slices in the prepared baking dish in an even layer. In a bowl, mix together the granulated sugar, flour, cinnamon and salt. Sprinkle the mixture over the apples, then pour 1/2 cup water over top.

Step 3

For the topping: In a separate bowl, mix the flour, oats, brown sugar, baking powder, baking soda and a pinch of salt. Stir while drizzling in the melted butter. Sprinkle the topping in an even layer over the apples.

Step 4

Bake until the topping is slightly crisp and golden brown, about 43 minutes. Serve warm or at room temperature on its own, with ice cream or with frozen custard.