1. Beat butter, sugar, egg and vanilla in large bowl until fluffy. Add 1 cup flour and baking soda; beat until blended. Remove 3/4 cup batter to small bowl; set aside. Add cocoa and remaining 3 tablespoons flour to remaining batter in large bowl; blend well.
2. Place peanut butter chips in small microwave-safe bowl . Microwave at MEDIUM (50%) 30 seconds or until melted and smooth when stirred. Immediately add to batter in small bowl, stirring until smooth. Divide chocolate dough into four equal parts. Roll each part in a log 7 inches long and about 1 inch in diameter. Between plastic wrap or wax paper, roll each part into logs about 1 inch in diameter and 7 inches long. Repeat with peanut butter dough. Wrap the eight rolls individually in wax paper or plastic wrap. Refrigerate several hours until very firm.
3. Heat oven to 350°F. Remove rolls from wax paper. Place 1 chocolate roll and 1 peanut butter roll side by side on a cutting board. Top each roll with another roll of the opposite flavor to make checkerboard pattern. Lightly push rolls together; repeat with remaining four rolls. Working with one checkerboard at a time (keep remaining checkerboard covered and refrigerated), cut into 1/4-inch slices. Place on ungreased cookie sheet.
4. Bake 8 to 9 minutes or until peanut butter portion is lightly browned. Cool 1 minute; remove from cookie sheet to wire rack. Cool completely. Makes about 54 cookies.