Line a large cookie sheet or baking pan with parchment paper or a silpat liner.

Preheat oven to 350°.

In a stand mixer, beat butter & sugars until well combined. Add eggs and vanilla, beating well until combined.

Place flour, xanthan gum, baking soda, salt, and cocoa powder into a large bowl and whisk together to mix.

Add the flour mixture to the wet ingredients, mixing slowly mixing just until combined.

Using a spatula, gently stir in chopped candy bars and/or candy pieces.

With a medium cookie scoop , scoop dough onto lined cookie sheets, leaving about 2" space between cookies. I did 6 cookies per sheet on my large cookie sheets.

Press additional candy onto surface of cookie balls. (This is just for looks really. I did about 3 pieces of Reese's and a candy bar chunk on the surface of each.)

Bake at 350° for 14-16 minutes, until set.

Let cool on baking sheet for about 5 minutes before transferring to a cooling rack.

Makes about 28 cookies.