Add sugar to melted butter. Stir until smooth. Let cool in the fridge back to room temperature before adding egg (we don't want it to scramble). Mix in a beaten egg. Cream in the peanut butter.
Mix together the salt, rice flour, arrowroot powder and baking soda. Arrowroot can be substituted with cornstarch, tapioca flour or even more rice flour although the texture will be affected. Sift gradually into the wet mixture.
Chill the cookie dough until it is semi-firm (about 20 minutes). Roll into teaspoon size balls.
Place peanut butter balls onto a non-stick baking sheet or parchment paper. Press down with a fork.
Bake for 10 minutes or until the cookie edges are lightly browned. Watch them carefully so that they don't burn. Rice flour burns more quickly than regular flour.
Remove from oven. Let sit for 5 minutes as they will be too soft to remove initially.
Try not to eat the whole batch!
Optional: dip the bottoms in chocolate for an extra delicious treat.
There are 111 calories in 1 serving of Gluten Free Peanut Butter Cookies.