The gluten-free part is just a bonus.  Thanks to Add A Pinch for this recipe.

INGREDIENTS
1 cup creamy peanut butter
1 cup brown sugar
3/4 teaspoon baking soda
1 egg
1 1/2 teaspoons vanilla
Garnish:
Sea salt
Coarse sugar

DIRECTIONS

Presheat oven to 350 degrees F.

Line a rimmed baking sheet with parchment paper or silicon baking mat.

Cream together peanut butter, sugar, baking soda, and sea salt until well blended. Add in egg and vanilla until well incorporated.

Drop tablespoon scoops of cookie dough batter onto prepared baking sheets. Press tops with fork. Place in oven and bake for 8-10 minutes. Remove from the oven before they have begun to brown. While still warm, garnish with sprinkles of optional garnishes, if desired.

Allow to cool slightly before removing to a cookie tray.