4 egg whites, at room temperature
1 cup whole milk, divided (1/4 cup and 3/4 cup)
2 1/2 teaspoons vanilla extract
3 cups cake flour
1 1/2 cups granulated sugar
4 teaspoons baking powder
1 teaspoon salt
3/4 cup (1 1/2 sticks) unsalted butter (cut into small pieces), at room temperature
Preheat the oven to 350ºF. Grease and flour three eight-inch cake pans (or use nonstick spray) and set aside.
In a small bowl, stir together the egg whites, ¼ cup milk, and the vanilla extract and set aside.
Place the flour, sugar, baking powder and salt in the bowl of a stand mixer fitted with the paddle attachment and combine on low speed. Scatter the butter pieces on top of the flour mixture and add the remaining milk. Blend on low speed until the dry ingredients are moistened. Add the egg white mixture a little at a time and beat on medium speed until just combined. Pour the batter evenly into the prepared pans. Bake for approximately 20 minutes or until a toothpick inserted in the center comes out clean. The cakes will appear slightly golden on top, not browned. Cool the cakes in the pans for 10 minutes. Transfer the cake to a wire rack and cool completely. While the cake is cooling, make your icing.
3 cups granulated sugar, divided (2 1/2 cups + 1/2 cup)
3 tablespoons light corn syrup
1 1/2 cups whole milk
1/4 cup (1/2 stick) unsalted butter, at room temperature
1 teaspoon vanilla extract
1/8 teaspoon salt
In a saucepan over medium heat, combine 2 1/2 cups sugar, corn syrup, and milk. Stir continuously until the sugar dissolves and no longer has a granular feeling. Keep warm over low heat.
In a separate deep, heavy saucepan, add the remaining 1/2 cup sugar and spread evenly over the bottom. Cook over medium heat without stirring until the sugar dissolves and begins to turn an amber color. You may “swirl” your pan if necessary to re-distribute sugar while cooking.
As soon as the sugar turns colors, carefully add the warm milk mixture into the heavy saucepan. It will bubble up vigorously and sizzle and the caramel on the bottom will harden.
Cook over medium heat, stirring constantly until the caramel dissolves and the liquid turns caramel color. Then cook without stirring until the mixture reaches soft-ball stage (235°F) on a candy thermometer. Remove from heat. Stir in the butter, vanilla, and salt.
Set aside to cool for 15 minutes. Mix until the icing is thick and the consistency appropriate to spread, about 15 minutes. A hand held electric mixer on medium speed works well for this purpose.