Use a sharp knife to cut each dough ball in half.
Roll each half between your hands into a ball, then flatten it slightly with your hands.
Roll one of each flavor together to marble them, then place them back on the tray.
Chill them again in the freezer until completely frozen solid, about 20-25 minutes.
Preheat the oven to 350 F/180 C.
Roll each cookie in coarse sugar, then bake them spaced 2-3 inches apart for 11-13 minutes, or until the peanut butter side has lightly golden brown edges.
Once out of the oven, press extra chocolate chips into the chocolate side if desired.
Let them cool completely on a wire cooling rack then enjoy!