In 9 x 13 glass baking dish add 2 T butter, put dish in oven and melt the butter, while you make the berry filling below.
Filling:
In saucepan, mix water, sugar, and butter or margarine and boil. Lower heat.
Add 2 T flour to thicken. Whip with whisk to remove lumps.
Simmer on low heat, until desired thickness. Do not scorch.
Crust:
In a large mixing bowl sift together the flour and baking powder.
Add the sugar and milk.
Mix well and pour into the baking dish that has 2 T butter or margarine already melted in it. Pour berry filling gently over the entire surface. DO NOT STIR.
Bake at 350 degrees for about 40 minutes, until crust on top is golden brown.