3 ounces melted semi-sweet chocolate
1 cup softened butter
1 cup Splenda granulated
2 eggs
2 teaspoons vanilla extract
4 cups flour
1 teaspoon baking powder
1/4 teaspoon salt

Beat butter till creamy. Gradually add Splenda and beat well. Add eggs one at a time, mixing well after each addition. Stir in vanilla. Combine dry ingredients. Gradually add to butter mixture. Do not overbeat. Divide dough in half and stir chocolate into half. Place on lightly floured surface.
Checkerboard
Shape each dough into two 1 inch diameter rectangular logs. Cut each log crosswise into quarters. Reassemble logs, alternating chocolate and vanilla to form checkerboard pattern.
Pinwheel
Roll chocolate dough into two 8x9 inch rectangles. Roll vanilla dough into two 8x10 inch rectangles. Place chocolate layers on top of vanilla so that vanilla extends 1 inch beyond chocolate. Roll as for a jelly roll.
Striped
Divide each dough into 3 balls. Roll each into 7 1/2x3 inch rectangle. Cut each rectangle into 5 strips. Stack 5 alternating flavor strips.
Assembly
Wrap logs of dough in plastic wrap and chill 1 hour till slightly firm or freeze up to 3 months. Heat oven to 350°F. Lightly grease baking sheets. Slice cookies 1/4 inch thick and place on prepared sheets. Bake 8-10 minutes till edges are lightly browned. Cool slightly on sheets before removing to racks to cool completely.