Aunt Baby's Checkerboard Cookies

Note: For more colorful cookies, substitute red or green food coloring for cocoa. Sift together flour, dry milk, baking powder, and salt. Set aside. Using an electric mixer, cream the butter and stir in vanilla. Gradually add sugar; beat until light and fluffy. Add well-beaten eggs, blending until smooth. Add dry ingredients and mix until well blended. Divide dough in half. Stir cocoa into one half, blending well. Shape each half into a rectangle, about 2" x 2" x 6". Tightly wrap in waxed paper. Chill at least 30 minutes. Unwrap dough; cut each rectangle into quarters, lengthwise. Alternately place dark and white quarters side by side to form checker design. Rewrap in waxed paper and chill slightly. Slice dough into 1/8-inch pieces and place on ungreased cookie sheet. Bake at 350 degrees for 12 minutes.