Lightly grease 9 x 13 pan.
Heat oven to 350 degrees.
Drop rhubarb into pan with butter. (Break butter into a few pieces.)
Sprinkle 1/2 cup sugar over top of rhubarb and butter.
Mix shortening, 1/4 cup sugar and egg until thoroughly combined.
Combine flour, salt and baking powder; stir till combined.
Add milk to shortening mixture, along with dry ingredients. Lightly stir until combined.
Drop batter on top of rhubarb, sugar and butter.
Bake for one hour. (Check for a few minutes sooner, to avoid the batter from browning too much.)
Cool and eat.