In a large bowl, cream the peanut butter, butter and sugars until light and fluffy, 5-7 minutes. Beat in egg. Combine the flour, baking powder, baking soda and salt; gradually add to creamed mixture and mix well., For the chocolate dough, in another large bowl, cream butter and sugars until light and fluffy, 5-7 minutes. Beat in egg and vanilla. Combine the flour, cocoa, baking powder, baking soda and salt; gradually add to creamed mixture and mix well., Divide each portion in half. Knead 1 peanut butter and 1 chocolate portion together 5-10 times or until it just begins to swirl. Shape into a 10-in. log. Wrap in waxed paper. Repeat with the remaining dough. Refrigerate 3-4 hours or until firm. , Preheat oven to 350°. Unwrap dough and cut into 1/4-in. slices. Place 2 in. apart on lightly greased baking sheets. Bake 6-8 minutes or until bottoms are lightly browned. Cool 2 minutes before removing from pans to wire racks. Freeze option: Place wrapped logs in a freezer container; freeze. To use, unwrap frozen logs and cut into slices. If necessary, let dough stand a few minutes at room temperature before cutting. Bake as directed.