Step 1

Preheat the oven to 350°F/175°C. Line one seven-inch pan and one six-inch pan with parchment rounds and grease with non-stick cooking spray. Set aside.

Step 2

Mix together 1 1/2 cups of flour, 1 1/2 cups sugar, 1 1/4 tsp baking powder, and 1/2 tsp salt in a stand mixer with a paddle attachment or in a large bowl with a hand mixer until fully combined.

Step 3

Mix 1/2 cup of room temperature butter slowly into the dry ingredients on a low speed. Continue to mix until no large chunks of butter remain and the mixture becomes crumbly.

Step 4

Pour in 1/2 cup of egg whites and mix on low until incorporated. Then mix in 3/4 cup of buttermilk, 1 Tbsp of oil, and 1 tsp vanilla on a low speed until fully incorporated. Scrape down the sides of the bowl with a spatula, then beat on medium-low speed for about 30 seconds. This helps make sure everything is properly mixed together and lightens the texture of the cake layers.

Step 5

Divide batter between the two prepared cake pans, filling them roughly the same height.

Step 6

Bake for 35-38 minutes or until a skewer comes out with a few moist crumbs. Let the layers cool in the pans for 10 minutes, then run an offset spatula around the perimeter of the pan to separate the cake from the pan. Place the cake layers into the freezer for 45 minutes to accelerate the cooling process.

Step 7

Once the layers have fully cooled, level the top of both layers using a serrated knife. While these layers bake pretty flat, it's important that the layers are totally flat because we'll be stacking them upright!

Step 8

While the cake layers bake and cool, make the buttercream frosting. Beat 2 cups of unsalted butter on a medium speed for 1 minute in a large bowl with a hand mixer or in a stand mixer fit with a paddle attachment.

Step 9

Add in 1 Tbsp vanilla extract and 1/2 tsp salt. Mix on a low speed until the ingredients are combined.

Step 10

Gradually mix in 7 cups of powdered sugar and 2 Tbsp of heavy cream on a low speed. Scrape the sides and bottom of the bowl as needed.

Step 11

Once fully mixed, check its consistency. If the frosting seems too thick, add in additional heavy cream (1 tsp at a time). If the frosting is too thin, add in more powdered sugar (quarter of a cup at a time). If your frosting looks broken, add in more room-temperature butter, 1 Tbsp at a time until it comes back together.

Step 12

Place 1 cup of frosting into a separate, medium-sized bowl and color it a bright shade of green with gel food coloring. Put this frosting into a small piping bag with a Wilton 104 tip (or any small petal tip). Seal the top of the bag with a rubber band or piping tip. This will be used to make the lettuce on this cake.

Step 13

Place 1 1/2 cups of frosting into the same bowl the green frosting was made in and mix in 1/4 cup of cocoa and 1 Tbsp of heavy cream to make chocolate buttercream. To create the "beef" in this taco cake, mix 1/2 cup of this chocolate frosting with 1 cup of crushed Oreos in a different bowl. Cover and set aside. Place the rest of the chocolate frosting in a small piping and cut a 1-inch opening at the base of the bag. Seal the top of the bag with a rubber band or piping tip. This will be used to cover the middle layer of the cake.

Step 14

Add 1/4 cup of uncolored frosting into a small piping bag and cut a 1-inch opening at the base of the bag. This will be the sour cream! Set aside.

Step 15

Color the remaining frosting a bright shade of yellow with gel food coloring. Cover the yellow frosting flush with plastic wrap and set aside.

Step 16

Chill the cake layers in the freezer for 20 minutes before assembling this cake if possible. It will make them so much easier to stack upright and frost!! If you made the layers ahead of time and they're already frozen, let the layers sit out for 20 minutes to thaw, then assemble the cake. You want them to be cold to the touch, but not fully frozen.

Step 17

Cut the cake layers in half. Spread 2 Tbsp of yellow buttercream across the center of the cake board where the cake layers will go. This will help keep them in place.

Step 18

Place one of the halves of the 6-inch cake layer in the center of the cake board vertically. Cover the entire cake layer with an even layer of chocolate buttercream. This layer is going to be completely covered, so don't worry about making the frosting perfect on this layer.

Step 19

Place the two halves of the 7-inch cake round vertically against the frosted layer and cover these two layers with yellow buttercream. These two layers will be the taco's shell.

Step 20

Smooth using a bench scraper or acetate sheet, then add the crushed Oreo/chocolate frosting mixture on top of the 6-inch cake layer. Next, pipe on some green buttercream on top of the Oreo mixture to look like lettuce.

Step 21

Gently place some of the colored shredded coconut on top, then add the red fondant cubes to look like diced tomatoes. The last step is to top the cake with a dollop of white buttercream to look like sour cream. Then enjoy!