Heat oven to 350?.

Sift together the flour, baking powder, baking soda and salt, set aside.

Cream the butter, shortening, and both sugars in a large bowl with an electric mixer at medium speed until light and fluffy.

Add eggs one at a time, beating well after each addition, then mix in the peanut butter.

Add the flour mixture by the cupful and beat at low speed to mix well.

Shape the dough into 1 inch balls and place on ungreased baking sheets about 2 inches apart. Press each cookie twice in each direction with a lightly floured fork to make a crosshatch design. Bake 10-12 minutes.