For Clara’s 7th birthday last year (she turns 8 in less than 2 weeks now!) we had an Under the Sea party and this was her mermaid cake. With THE BEST vanilla cake recipe from Sally (her site is my go-to for cakes), several youtube ombre frosting tutorials, and the sea creatures purchased from etsy, it wasn’t too hard to make!

I added some pretty sprinkles to the batter (instructions included in the notes below) and frosted the cake with Sally’s classic vanilla buttercream. I did use three 6-inch cake pans instead of the 9-inch ones called for in the recipe, with a slightly reduced baking time. (I can’t remember what I did with the extra batter but making a few cupcakes on the side isn’t a bad idea!) This really is a wonderfully light, yet moist, and flavorful vanilla cake.

In keeping with the Under the Sea theme we had a shark watermelon (thanks to my sister, Brooke, who took the time to carve it) and crab croissant sandwiches (olives and croissants are two of Clara’s favorite foods)!

There was also a veggie tray and dip that had a little crab hanging out it it…

… and bowls of goldfish crackers and pretzels and a plate of peanut butter and jelly starfish!

I’m so glad we had a big party for her 7th birthday since this year we’ll be celebrating under “lockdown”. Of course there will still be good food and lots of love and cake!

If you want details about specific ingredients or substitutions, etc. follow the links to Sally’s original post. There are also tons of positive reviews… I’m not the only one who loves this recipe!

Vanilla Layer Cake with Vanilla Buttercream Frosting

INGREDIENTS

Vanilla Cake:

3 and 2/3 cups cake flour (spooned and leveled)
1 tsp. salt
1 tsp. baking powder
3/4 tsp. baking soda
1 1/2 cups unsalted butter, softened to room temperature
2 cups granulated sugar
3 large eggs + 2 additional egg whites, at room temperature
1 Tbsp. pure vanilla extract
1 1/2 cups buttermilk, at room temperature

Vanilla Buttercream Frosting:

1 1/2 cups unsalted butter, softened to room temperature
6 cups powdered sugar
1/3 cup whole milk or heavy cream
1 1/2 tsp. pure vanilla extract
1/8 tsp. salt

DIRECTIONS

1. Preheat oven to 350 F. Grease three 9-inch cake pans, line with parchment paper, then grease the parchment paper. Parchment paper helps the cakes seamlessly release from the pans.
   
2. Make the cake: Whisk the cake flour, salt, baking powder, and baking soda together. Set aside.
   
3. Using a handheld or stand mixer fitted with a paddle or whisk attachment, beat the butter and sugar together on high speed until smooth and creamy, about 3 minutes. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. Beat in the 3 eggs, 2 egg whites, and vanilla extract on high speed until combined, about 2 minutes. (Mixture will look curdled as a result of the egg liquid and solid butter combining.) Scrape down the sides and up the bottom of the bowl as needed. With the mixer on low speed, add the dry ingredients just until combined. With the mixer still running on low, pour in the buttermilk and mix just until combined. You may need to whisk it all by hand to make sure there are no lumps at the bottom of the bowl. The batter will be slightly thick.
   
4. Pour batter evenly into cake pans. Weigh them to ensure accuracy, if desired. Bake for around 23-26 minutes or until the cakes are baked through. To test for doneness, insert a toothpick into the center of the cake. If it comes out clean, it’s done. Allow cakes to cool completely in the pans set on a wire rack. The cakes must be completely cool before frosting and assembling.
   
5. Make the frosting: In a large bowl using a hand-held mixer or stand mixer fitted with a whisk or paddle attachment, beat the butter on medium speed until creamy, about 2 minutes. Add confectioners’ sugar, milk, vanilla extract, and salt with the mixer running on low. Increase to high speed and beat for 2 minutes. Add more confectioners’ sugar if frosting is too thin, more milk if frosting is too thick, or an extra pinch of salt if frosting is too sweet.
   
6. Assemble and decorate: Using a large serrated knife, slice a thin layer off the tops of the cakes to create a flat surface. Discard (or crumble over ice cream!). Place 1 cake layer on your cake stand, cake turntable, or serving plate. Evenly cover the top with about 1 and 1/2 cups of frosting. Top with 2nd cake layer and evenly cover the top with about 1 and 1/2 cups of frosting. Top with the third cake layer. Spread the remaining frosting all over the top and sides. I use and recommend an icing spatula to apply the frosting.
   
7. Refrigerate cake for at least 1 hour before slicing. This helps the cake hold its shape when cutting.
   
8. Cover leftover cake tightly and store in the refrigerator for up to 5 days.

NOTE: To make a sprinkle cake, fold about 3/4 cup of sprinkles into the cake batter. Avoid nonpareils (the little balls), which tend to bleed their color.

From Sally’s Baking Addiction