Preheat your oven to 350°F (175°C) and prepare an 8x8-inch baking pan by greasing it or lining it with parchment paper.
In a medium bowl, whisk together the dry ingredients: gluten-free flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
In a large bowl, mix the wet ingredients: melted butter, granulated sugar, and brown sugar until smooth. Add eggs and vanilla extract, and beat until creamy.
Gradually add the dry ingredients to the wet mixture, stirring gently until just combined.
Fold in mini chocolate chips and half of the rainbow sprinkles until evenly distributed.
Pour the batter into the prepared baking pan, smooth the top, and sprinkle the remaining rainbow sprinkles on top. Bake for 25-30 minutes.
Allow the brownies to cool in the pan for at least 15 minutes before cutting into squares.