Preheat oven to 350°F (175°C).

Lightly grease 2-3 oven trays.

In a stand mixer, cream butter, peanut butter, brown sugar, and egg until combined.

Fold in gluten-free flour and baking soda.

Fold in roasted unsalted peanuts.

Roll heaped teaspoons of mixture into balls.

Place balls about 1 inch apart on prepared trays.

Press lightly with a fork to flatten.

Bake for 12 minutes, or until golden brown.

Let cool on trays for a few minutes before serving.