Preheat your oven to 350°F (175°C).
Grease an 8x8-inch baking pan with butter or cooking spray.
In a large mixing bowl, whisk together the gluten-free flour, granulated sugar, cocoa powder, baking powder, and salt.
In another bowl, mix the melted butter and creamy peanut butter until smooth. Add the eggs and vanilla extract, whisking until fully incorporated.
Pour the wet mixture into the dry ingredients and stir gently until just combined.
Add a spoonful of creamy peanut butter on top of the brownie batter and swirl it in for a marbled effect.
Fold in the crispy rice cereal and chocolate chips until evenly distributed.
Pour the brownie batter into the prepared baking pan and spread it evenly. Bake for 25-30 minutes.
Let the brownies cool in the pan for at least 15 minutes before cutting into squares.