*This recipe came with a cupcake cake pan I bought from Williams-Sonoma. This make enough batter that I filled the cake pan and I made a 9"x9" cake in another pan, so I think this recipe should work fine for two regular cake rounds or square pans.
I would multiply the frosting recipe by 4 or 5x to have enough for the filling and for decorating the outside.
3-2/3 C all-purpose flour
2 tsp. baking powder
1-1/4 tsp. salt
1-1/3 C unsalted butter
2-1/3 C granulated sugar
5 eggs, lightly beaten
4 tsp. vanilla extract
1-1/3 C milk
4 Tbsp. (1/2 stick) unsalted butter
1-1/2 C confectioner's sugar, sifted
1 Tbsp. milk
1/2 tsp. vanilla extract
Pinch of salt
Have all the ingredients at room temperature.
Position rack in the lower third of an oven and preheat to 325 degrees. Place a baking sheet on the lowest oven rack to catch any batter that might overflow. Grease and flour pan; tap out the excess flour.
Over a sheet of wax paper, sift together the flour, baking powder and salt, set aside.
In the bowl of an electric mixer fitted with the flat beater, beat the butter on medium speed until creamy and smooth, about 30 seconds. Add the granulated sugar and continue beating until light and fluffy, about 5 minutes, stopping the mixer occasionally to scrape down the sides of the bowl. Add the eggs a little at a time, beating well after each addition. beat in the vanilla just until incorporated, about 1 minute.
Reduce the speed to low and add the flour mixture in three additions, alternating with the milk and beginning and ending with the flour. Beat each addition just until incorporated, stopping the mixer occasionally to scrape down the sides of the bowl.
Spoon the batter into the prepared pan, filling the wells to no more than 1/2 inch of the rim and spreading the batter so the sides are higher than the center. Bake until the cake begins to pull away from the sides of the pan and a toothpick inserted into the center comes out clean, 70 to 80 minutes. Transfer the pan to a wire rack and let the cupcake cool in the pan for 15 minutes.
Gently tap the pan on the counter to loosen the cake. Set the rack over the cake, invert the pan onto the rack and lift off the pan. Let the cake cool completely, at least 2 hours, before assembling and decorating.
Meanwhile, make the buttercream frosting: In a small bowl, using a handheld mixer (I just used my Kitchenaid), beat the butter on medium speed until smooth and creamy, about 1 minute. Add the confectioner's sugar, milk, vanilla and salt and continue beating until light and fluffy, 2 to 3 minutes more.
Level the cake by using a serrated knife to gently saw off the top of your bottom layer. Spread desired amount of buttercream over the cut side of the cake layer. Place the flat, bottom side of the top layer on the buttercream. Gently press down to secure the two halves. cover the cake loosely with plastic wrap and refrigerate until the buttercream is firm, about 1 hour.
Decorate as desired.