Prep your pans: Heat the oven to 350°F (175°C). Grease and line two 8-inch round cake pans with parchment. Lightly flour with your gluten-free blend. This prevents sticking and helps with clean release.

Whisk dry ingredients: In a medium bowl, whisk the gluten-free flour, baking powder, and salt. Set aside. This evenly distributes leavening and prevents clumps.

Cream fats and sugars: In a large bowl, beat the softened butter, oil, granulated sugar, and brown sugar on medium speed for 2–3 minutes until light and fluffy. Scrape the bowl once to ensure even mixing.

Add eggs and vanilla: Beat in the eggs one at a time. Mix for 20–30 seconds after each egg until well incorporated. Stir in the vanilla (and almond extract or vanilla paste if using).

Alternate dry and wet: On low speed, add one-third of the dry mix, then half the buttermilk, another third of the dry, the whole milk, and finally the last third of dry. Mix just until combined. Do not overmix.

Rest the batter briefly: Let the batter sit for 5–8 minutes. This gives the gluten-free flour time to hydrate, improving texture and preventing grittiness.

Portion and level: Divide the batter evenly between the pans. Smooth the tops with a spatula and tap each pan gently on the counter to release air bubbles.

Bake: Bake for 22–28 minutes. The cakes are done when the centers spring back to a light touch and a toothpick comes out with a few moist crumbs. Avoid overbaking.

Cool: Let the cakes cool in the pans for 10 minutes. Run a thin knife around the edges, then invert onto a rack. Peel off parchment and cool completely.

Make the frosting: Beat butter until creamy. Gradually add powdered sugar, then vanilla, salt, and 1 tablespoon milk. Add more milk as needed for a smooth, spreadable consistency.

Assemble: Place one cake layer on a plate, add a generous layer of frosting, then set the second layer on top. Crumb coat the cake (a thin layer of frosting), chill 15 minutes, then finish frosting.