1-Step 1: Mix the dry ingredients Whisk the flour, baking powder, and salt together in a large bowl. This helps spread the baking powder evenly through the batter, which supports an even rise. If your baking powder is old, replace it before baking because stale leavening can leave the cake flat.

2-Step 2: Whip the eggs and sugar Beat the eggs on medium speed for about 30 seconds, then slowly add the sugar over 45 seconds. After that, beat on high speed for 7 minutes until the mixture turns white, thick, and glossy. It should nearly triple in volume. This step matters a lot, so do not stop and start once the beating begins. The egg mixture should look pale, airy, and ribbon-like. That is the signal that your cake has the structure it needs.

3-Step 3: Warm the milk and butter While the eggs are beating, gently heat the milk and butter together until the butter melts but the milk stays hot. Do not let the mixture cool before using it. The warmth helps create a smoother batter and supports a softer texture in the baked cake.

4-Step 4: Add the flour in stages Once the eggs are ready, add the flour mixture in three parts. Mix each addition briefly and gently until just combined. Overmixing here can knock out the air you worked so hard to build, so stop as soon as you no longer see dry flour.

5-Step 5: Mix the hot milk blend In the empty flour bowl, combine the hot milk-butter mixture, vanilla extract, and oil. Then add about 1 1/2 cups of the whipped egg mixture and whisk until smooth and foamy. This step helps lighten the milk mixture so it folds into the batter more easily.

6-Step 6: Finish the batter Slowly pour the milk mixture into the egg batter while mixing gently. Scrape down the bowl and mix briefly until the batter is smooth and pourable. It should look silky, not dense. If you see a few tiny bubbles, that is a good sign.

7-Step 7: Fill the pans and bake Pour the batter evenly into the prepared pans. Tap each pan on the countertop three times to knock out large air bubbles. Bake for about 30 minutes, or until the tops are golden and a toothpick inserted in the center comes out clean.

8-Step 8: Cool the cakes properly Let the cakes cool in the pans for 15 minutes, then turn them out onto wire racks. For flatter layers, cool them upside down so the slight dome settles down. Allow at least 2 hours of cooling before frosting, since warm cake will melt the buttercream.

9-Step 9: Make the vanilla buttercream Beat the softened butter on high speed for 3 minutes until pale and fluffy. Add the sifted icing sugar gradually in parts, mixing slowly at first so the powder does not fly everywhere. Once combined, beat on high for another 3 minutes until light and airy. Add vanilla and 2 to 4 tablespoons of milk, then beat briefly until you reach the texture you like.

10-Step 10: Frost and serve Once the cake is completely cool, spread the buttercream over the layers or over the top and sides. If the buttercream has been chilled, re-whip it first so it becomes soft and spreadable again. Slice and serve once the frosting is smooth and the cake is fully assembled.