01 - Preheat the oven to 350°F. Grease a 9-inch round cake pan and line the bottom with parchment paper.
02 - In a medium bowl, whisk together the gluten-free flour blend, cocoa powder, baking powder, baking soda, and salt until evenly distributed.
03 - Using an electric mixer on medium speed, beat the eggs, granulated sugar, and brown sugar until pale and thick, approximately 2 minutes.
04 - Mix the vegetable oil and vanilla extract into the beaten egg mixture until fully combined.
05 - Alternately add the dry ingredients and buttermilk to the wet mixture, beginning and ending with the dry ingredients. Mix just until smooth without overmixing.
06 - Pour the batter into the prepared cake pan and, if desired, scatter the chocolate chips evenly over the top.
07 - Bake for 32 to 36 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached.
08 - Let the cake cool in the pan for 10 minutes, then transfer it onto a wire rack to cool completely.
09 - Dust the cooled cake with powdered sugar and garnish with fresh berries or edible gold star sprinkles before serving.