Gluten-Free Single-Layer Yellow Cake

Ingredients

• Gluten-free non-stick cooking spray
• 1 1/4 cups white rice flour
• 1 cup granulated sugar
• 1/2 cup potato starch
• 1 1/4 teaspoons baking powder
• 3/4 teaspoon salt
• 1/2 teaspoon xanthan gum
• 1 stick unsalted butter, softened
• 2/3 cup milk or water
• 3 large eggs
• 2 teaspoons vanilla extract
• For the chocolate buttercream:
• 2 cups powdered sugar, sifted if lumpy
• 6 tablespoons cocoa powder, sifted if lumpy
• 1/2 teaspoon salt
• 4 tablespoons milk plus additional as needed

Directions

1. For the cake, move the oven rack to the middle position and heat the oven to 350 degrees F. Apply nonstick cooking spray to the baking pan, using either an 8x8x2-inch square pan or a 9x2-inch round pan, then put it aside.
2. In a large mixing bowl, whisk the white rice flour, granulated sugar, potato starch, baking powder, salt, and xanthan gum until combined. Add the butter, milk or water, eggs, and vanilla. With a handheld mixer, beat until the mixture becomes a thick batter, about 1 minute. Spoon it into the prepared pan and smooth it out evenly. Bake until a cake tester pushed into the center comes out clean, about 40 minutes. Set the cake, still in the pan, on a wire rack to cool. Once cool, frost with buttercream if desired, or finish with the citrus glaze.
3. For the chocolate buttercream, whisk the powdered sugar, cocoa powder, and salt together in a medium bowl. In a large bowl, beat the butter until it looks light. Add the powdered sugar-cocoa mixture and the milk, then cream everything together until smooth. If the icing needs thinning, mix in more milk, 1 tablespoon at a time, until it is thick but easy to spread.