Sift together first three ingredients onto waxed paper. Crush the peanut brittle. Beat butter and peanut butter until well blended in a lg bowl with electric mixer at high speed. Beat in the sugars, and vanilla. Add dry ingredients slowly and 1 1/4 cup peanut brittle crushed. Spread dough into a greased 15 x 10 x1 inch jelly roll pan. Sprinkle remaining peanut brittle on top. Bake 375 for 20 mins. Cool in pan on wire rack. Cut into 2 inch bars or triangles. Decorate with a vanilla frosting if desired and whole peanuts.
**Jelly roll pan for those who are wondering is simply a cookie sheet with sides.
