Line two cookie sheets with parchment paper.

In a large mixing bowl, whisk together the sugar cookie mix and cocoa powder.

Beat in the softened butter and egg using a hand or stand mixer until a thick dough forms.

Scoop out a large ball of dough using a 1 1/2 tablespoon cookie scoop and flatten it into a disc.

Place two unwrapped Rolos in the center of the disc and gently form the dough into a smooth ball.

Roll the ball in sanding sugar or powdered sugar, if desired, then place on the prepared cookie sheet.

Repeat with the remaining dough, placing cookies about 2 inches apart on the sheets.

Cover the cookie sheets with plastic wrap and refrigerate for at least 30 minutes.

Preheat the oven to 350°F (175°C) several minutes before baking.

Remove cookies from the refrigerator, discard the plastic wrap, and bake for 10-15 minutes or until the edges are set and the tops begin to crack.

Remove from the oven and cool on the sheet for at least 5 minutes before transferring to a cooling rack.