Classic White Cake
1/4 tsp. salt
3/4 cup butter, softened
1 1/2 cups sugar
2 tsp. vanilla extract
6 large egg whites
3/4 cup milk
1. Position a rack in the middle of the oven and preheat to 350 degrees.
2. Combine the flour, baking powder, and salt in a bowl, mixing well.
3. Place the butter and sugar in the bowl of a heavy-duty mixer fitted with the paddle attachment and beat on medium speed for about 5 minutes, or until very soft and light. Beat in the vanilla.
4. Whisk together the egg whites and milk by hand in a medium mixing bowl until just combined.
5. Reduce the mixer speed to low and beat in one-quarter of the flour mixture, then one-third of the milk mixture, stopping and scraping down the bowl and beater after each addition. Beat in another quarter of the flour, then another third of the milk mixture. Scrape again. Repeat with another quarter of the flour and the remaining milk mixture; scrape. Finally, beat in the remaining flour mixture.
6. Scrape the bowl well with a large rubber spatula. Pour the batter into the prepared pans and smooth the tops.
7. Two 9-inch round cake pans, buttered and bottoms lined with buttered parchment or wax paper
8. Bake the layers for about 30 to 35 minutes, until they are well risen and firm and a toothpick inserted in the center emerges clean.
9. Cool the layers in the pans on racks for 5 minutes, then unmold onto racks to finish cooling right side up.