Preheat the oven to 350 degrees and get out a 15"x10" jelly roll pan. Cream together the butter, shortening and both sugars until thoroughly blended. Add the egg and beat until light and fluffy, then beat in the hot water and vanilla.
Combine the flour, baking soda and baking powder, then stir and toss them together. Add to first mixture and stir until thoroughly blended. Stir in the Wheaties, oatmeal and nuts, mixing well. Spread the dough evenly in the ungreased pan. Bake for about 20 minutes, or until puffed and slightly golden around the edges. Remove from the oven and cut into 3 1/2" squares. Cool completely and store in an air tight container, or wrap well and freeze. Makes approximately 12 BIG bars.
