Step 1: A few hours before baking, place mini marshmallows in the freezer for at least 2-3 hours.

Step 2: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Step 3: In a medium bowl, whisk together gluten-free flour, baking soda, and sea salt.

Step 4: In a large mixing bowl, cream together softened unsalted butter, granulated sugar, and packed brown sugar until fluffy.

Step 5: Add creamy peanut butter, large egg, and vanilla extract to the butter-sugar mixture and blend until smooth.

Step 6: Quickly fold in the frozen marshmallows into the batter.

Step 7: Gradually mix the dry flour mixture into the wet ingredients until just combined.

Step 8: Scoop balls of dough onto the baking sheet, spacing them about 1-2 inches apart.

Step 9: Bake in the preheated oven for 10-11 minutes until lightly golden around the edges.

Step 10: Cool the cookies on the baking sheet for about 10 minutes before transferring to a wire rack.