01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk together gluten-free flour, cocoa powder, baking soda, and salt in a medium bowl. Set aside.
03 - Beat butter, brown sugar, and granulated sugar with an electric mixer on medium speed until light and fluffy, about 2 minutes.
04 - Add eggs one at a time, beating well after each addition. Mix in vanilla extract.
05 - Gradually add the dry ingredients to the wet ingredients, mixing on low speed just until combined.
06 - Fold in chocolate chips, chopped hazelnuts, and puffed rice cereal until evenly distributed.
07 - Scoop heaping tablespoons of dough onto prepared baking sheets, spacing about 2 inches apart.
08 - Bake for 10-12 minutes, or until edges are set but centers are still slightly soft.
09 - Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.