Leave remaining cookie dough portion alone.
I find it best to portion each dough ball out into 1 teaspoon size portions. Then it becomes easy to grab one tiny cookie dough portion and press together forming the Neapolitan stripe look you are going for.
Place cookie dough on baking pan with parchment paper and bake in a preheated oven to 350 degrees.
Bake for 7-9 minutes or until edges are set and tops are no longer glossy. Remove from oven and allow to cool on baking sheet for a minute or two before removing to a cooling wire rack to cool completely.
