Mix butter, flour and brown sugar until crumbly.
Place peach slices, overlapping slightly if needed, in a single layer across the jam.
Sprinkle with the 1 tablespoon of sugar.
Sprinkle on the streusel topping.
Bake 25-30 minutes or the filling is bubbling and the topping is golden brown.
Cool completely before cutting.
Top with ice cream and a caramel drizzle, if desired.