Rectangle Cake with Vanilla Buttercream

Rectangle Cake with Vanilla Buttercream Recipe

This cake was intended to be a sheet cake, but I impatiently took the cake out of the pan before it was completely cool, and sadly found myself with broken pieces. Frustrated, I almost threw it away, but then realized I could turn it into a rectangle-shaped cake by making the broken pieces the middle layer. It was a big hit with my kids, and no one knew it was almost a disaster.

Ingredients

Rectangle Cake with Vanilla Buttercream Recipe
  • 1 sheet cake (your favorite 9 x 13 sheet cake recipe will work here), baked and cooled
  • 2 cups (4 sticks) unsalted butter, room temperature
  • 1 tablespoon pure vanilla extract
  • ¼ teaspoon salt
  • 4 cups powdered sugar
  • Food coloring, optional

Directions

Rectangle Cake with Vanilla Buttercream Recipe

In the bowl of a standing mixer, beat the butter until creamy. Scrape down the sides and add the orange zest, juice, vanilla, Triple Sec (if using) and salt. Mix on low until combined, and then beat the ingredients together for a minute. Turn the mixer back to low, and slowly add the powdered sugar, mixing until combined. Increase the speed to medium-high, and then beat 6-8 minutes until light and fluffy.

How To Assemble

Rectangle Cake with Vanilla Buttercream Recipe Rectangle Cake with Vanilla Buttercream Recipe Rectangle Cake with Vanilla Buttercream Recipe Rectangle Cake with Vanilla Buttercream Recipe

Cut the sheet cake into three equal pieces. Place one piece cut side up on a serving plate. With a knife or offset spatula, spread the top with about ¾ cup. Place the second layer on top (if you have any broken pieces, fit them in here), and repeat with the frosting. Put the third piece of cake on top cut side down, and spread the frosting evenly on the top and sides of the cake. Decorate as desired.

Rectangle Cake with Vanilla Buttercream Recipe

Enjoy!

  • Ivy Brenson

    This cake would be a great present for my dear friend David J Salmon birthday:) It will be my first time I cook something I hope I will not fail:)

  • Brooke Happel

    This is beautiful! Can you please tell me how much juice, zest and triple sec go into the frosting? I see them listed in the instructions (“Scrape down the sides and add the orange zest, juice, vanilla, Triple Sec (if using) and salt”), but not in the ingredients list… thank you!!!

  • AnnaZed

    I love this! I particularly like the way that you have affixed the sprinkles of two different gauges on the sides at top. I am actually a very good baker, but I have never figured out how to to get sprinkles to fix that way on the sides of a cake. How do you do that?