Cream butter with 1/2 cup powdered sugar, and salt. Add flour and mix well. pat it out in a greased 9x13 inch pan with your fingers. Bakes at 350 degrees for 15 minutes. That makes the shortbread crust. Remove from oven.
(Don't turn oven off!)
Mix eggs with melted butter and white sugar. Add baking powder, salt, and flours and mix thoroughly. (Hand mixer will do the job if you're tired of stirring.)
Melt the chocolate chips in a small double boiler, a pan over hot water on the stove, or nuke them for 3 minutes in the microwave on high. (Be sure to stir the chips or they could maintain their shape ever after they're melted.)
Add the melted chocolate chips to your bowl and mix thoroughly.
Pour this mixture on top of the pan you just baked and tip the pan so it covers all the shortbread crust. Stick it back into the oven and bake it for another 25 minutes. Then remove it from the oven and sprinkle on additional powdered sugar.
Let it cool thoroughly and cut into brownie-sized bars. You can refrigerate these, but cut them before you do. They get pretty solid when they're cold.