4. Transfer 1 3/4 cups of the dough to another bowl and set aside. Add the cocoa powder to the remaining dough in the mixer and mix on low speed until blended. Add half of the chocolate pieces and about half of the pecan pieces and mix until blended. Stir the remaining half of the chocolate and pecan pieces into the remaining light-colored dough. Fill half of a 1 tablespoon scoop or measure with the light dough, making it well rounded, not level. Fill the remaining half with the chocolate dough. I took a big pinch of white dough in my left hand and of the chocolate with my right hand and sandwiched them together. They were probably 1 Tbsp worth of dough together. Roll the doughs into a ball and place it on an ungreased baking sheet. Flatten it into a 1 1/2-inch disc with your palm (wet it first, to prevent sticking). Repeat to form more cookies, spacing them 2 inches apart. I got 9 cookies to a sheet. Bake, 1 sheet at a time, for 8 to 10 minutes, until the lighter dough just begins to color. Let the cookies cool on the baking sheet for 5 minutes, then transfer the cookies to a wire rack and cool completely.
Storage: in an airtight container at room temperature for up to a week.