Chocolate and Vanilla Checkerboards

In a large mixing bowl beat the butter or margarine with an electric mixer on medium to high speed for 30 seconds. Add the granulated sugar, brown sugar, and baking powder; beat till combined. Beat in the egg and vanilla. Beat in as much of the flour as you can with the mixer. Stir in any remaining flour with a wooden spoon. Divide dough in half.

Knead melted chocolate into half of dough till combined. Shape plain and chocolate halves of dough into 8-inch logs. Wrap each in waxed paper or plastic wrap. Chill for 2 hours, or till firm. Cut each chilled log lengthwise into quarters; reassemble logs, alternating chocolate and vanilla quarters. Wrap and refrigerate for 15 to 30 minutes, or till well chilled.

Cut dough into 1/4-inch-thick slices. Place 2 inches apart on ungreased cookie sheets. Bake in a preheated 375 degrees F oven for 8 to 10 minutes, or till edges are firm and bottoms are lightly browned. Remove cookies and cool on a rack.