Preheat the oven to 400 degrees and grease an 8 x 8-inch baking dish.
Peel and core the Peaches and cut them into thin slices. Spread the slices in the prepared baking dish.
Combine the flour, and sugar, if using, in a medium bowl. Cut in the butter with a pastry blender or fork until the mixture is crumbly. Spread evenly over the peaches.
Bake uncovered until golden brown, 40 to 45 minutes.
To double this recipe, bake it in a 13 x 9-inch pan for 50 to 60 minutes.
