In a large bowl, cream butter and sugars until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in vanilla. Combine flour and baking powder; add to creamed mixture just until moistened.
Press into a greased 13x9-in. baking pan. Bake at 350° for 8-10 minutes or until lightly browned.
Meanwhile, melt butter in a large saucepan over medium heat. Remove from the heat; stir in sugar and vanilla. Add eggs, one at a time, stirring well after each addition. Combine the flour, cocoa, baking powder and salt; stir into butter mixture just until combined. Spread over warm blond layer.
Bake for 20-25 minutes or until a toothpick inserted in the center comes out clean (do not overbake). Cool on a wire rack.
Cut into 36 rectangles (3-1/4x1 in.). With decorating gel, draw a line dividing each rectangle in half widthwise; attach baking bits with dabs of decorating gel to resemble dominoes.