Line a large 18” x 13” (with at least a 1” rim) baking sheet with parchment paper and spray with non-stick baking spray. When lining the baking sheet, the parchment paper should come up over the sides slightly so the cookie base is easy to lift out once chilled. Set aside for now.

In a medium bowl, whisk together gluten free flour, sifted cocoa powder, xanthan gum (if needed), baking powder and salt. Set aside for now.

In a large bowl, whisk together melted butter, granulated sugar, brown sugar, eggs and vanilla extract. Whisk together until fully combined.

Whisk dry ingredients into wet ingredients until fully combined.

Spread batter evenly onto the prepared baking sheet.

Bake 17 to 19 minutes or until cookie base is set. Do not under bake as an under baked cookie base will break apart too easily. It will be soft but shouldn’t still look raw in the middle. Should look like a baked brownie.

Let the cookie base cool completely on the baking sheet.

Once cool, transfer the cookie base (still on the baking sheet) into the freezer for an hour. It’s important to freeze the cookie base before assembling the ice cream sandwiches. This helps the cookie base stay firm while layering.

Take the ice cream out of the freezer and let sit out at room temperature for about 15 minutes so it softens up. The ice cream should be softened but not melted. It needs to be spreadable but still frozen enough to not leak out the sides of the sandwiches.

Cut the large cookie base in half and transfer it to a large piece of food-safe plastic wrap.

Evenly spread the ice cream mixture on top of one half of the frozen cookie base.

Gently lift the other half of the cookie base and place it on top of the ice cream layer.

Wrap well in food-safe plastic wrap and place back into the freezer for at least 8 hours (preferably overnight).

Once frozen solid, use a sharp knife to cut into rectangles or squares (depending on the serving size you want for each sandwich).