Homemade Vanilla Cake

Prep

1. Heat oven to 350°F. Grease two 8-inch or 9-inch round cake pans. Line bottoms with parchment, then grease the parchment. Light flouring is optional but helpful if your pans are moody.
   Note: If using convection, reduce to 325°F and start checking a bit early.
2. In a medium bowl, whisk together flour, baking powder, and salt.
3. In a small bowl or measuring cup, stir together milk and sour cream (if using). If not using sour cream, you can simply use the milk as-is, or swap in plain Greek yogurt in the same amount.

Make the batter

1. Cream butter and sugar: In a stand mixer (or with a hand mixer), beat butter and granulated sugar on medium-high until light and fluffy, about 3 to 4 minutes. Scrape the bowl once or twice.
2. Add eggs and vanilla: Add eggs one at a time, mixing well after each. Mix in vanilla. If the mixture looks slightly curdled, do not panic. It will come back together when the flour goes in.
3. Alternate dry and wet: On low speed, add the flour mixture in 3 additions, alternating with the milk mixture in 2 additions. Start and end with flour. Mix just until you stop seeing dry streaks. Do not overmix. A tender crumb loves restraint.
4. Divide and smooth: Split batter evenly between pans and smooth the tops.

Bake and cool

1. Bake for 24 to 30 minutes, depending on pan size and oven. 9-inch pans usually bake a bit faster; 8-inch layers are thicker and may need the longer end. The center should spring back lightly and a toothpick should come out clean or with a few moist crumbs.
   Optional precision tip: the center will read about 200 to 205°F on an instant-read thermometer.
2. Cool in pans for 10 minutes, then turn out onto a rack, peel off parchment, and cool completely before frosting.

Make the buttercream

1. Beat butter on medium-high until creamy, about 2 minutes.
2. Add powdered sugar: Mix in powdered sugar 1 cup at a time on low, then increase speed to medium. Add vanilla and a pinch of salt.
3. Adjust texture: Add milk or cream 1 tablespoon at a time until spreadable and fluffy. Beat 1 more minute on medium-high. Taste and add another pinch of salt if it needs brightness.

Frost and finish

1. If your cake layers domed, level them with a serrated knife. (Snack on the scraps. It is tradition.)
2. Place one layer on a plate or cake stand. Add a thick layer of buttercream and spread to the edges.
3. Add second layer, then apply a thin crumb coat all over. Chill 15 minutes if you want extra-clean sides.
4. Finish frosting with the remaining buttercream. This amount is enough for a comfortable fill and a simple coat on 8-inch or 9-inch layers. If you want tall swirls, borders, or heavy piping, you may want to make 1 1/2 batches.
5. Slice with a sharp knife, wiping between cuts for neat pieces.