Yellow (Vanilla) Cake

18 tablespoons (2 1/4 sticks) unsalted butter at room temperature
3 cups sugar
6 extra-large eggs at room temperature
1 cup sour cream at room temperature
1 1/2 teaspoons pure vanilla extract
3 cups flour
1/3 cup cornstarch
1 teaspoon kosher salt
1 teaspoon baking soda

Heat the oven to 350 degrees F. Butter and flour an 18 by 13 by 1 1/2-inch sheet pan. Cream the butter and sugar in the bowl of an electric mixer fitted with the paddle attachment on high speed, until light and fluffy. On medium speed, add the eggs, 2 at a time, then add the sour cream and vanilla. Scrape down the sides and stir until smooth. Sift together the flour, cornstarch, salt, and baking soda in a bowl. With the mixer on low speed, add the flour mixture to the butter mixture until just combined. Pour into the prepared pan. Smooth the top with a spatula. Bake in the center of the oven for 20 to 30 minutes, until a toothpick comes out clean. Cool to room temperature.