Ingredients
1 box White Cake Mix
1 ¼ cups Milk
½ cup Vegetable Oil
4 large Egg Whites
2 tsp Vanilla Extract
2 sticks (1 cup) Unsalted Butter, softened
4 cups Powdered Sugar, sifted
2–4 tbsp Heavy Cream or Milk
1 tsp Vanilla Extract
Pinch Salt
Gel Food Coloring (various shades of blue, green, purple)
½ cup Assorted Sprinkles (ocean-themed, pearl, blue, green, purple, white)
Edible Glitter (optional)
Candies (optional, e.g., chocolate shells, gummy fish)
Instructions
- Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans (or line with parchment paper) and set aside
- In a large bowl, combine the white cake mix, 1 ¼ cups milk, vegetable oil, egg whites, and 2 tsp vanilla extract. Beat with an electric mixer on low speed for 30 seconds, then scrape down the sides of the bowl. Increase to medium speed and beat for 2 minutes, until the batter is smooth and well combined
- Divide the cake batter evenly into three separate bowls. Leave one bowl of batter white. In the second bowl, add a few drops of light blue gel food coloring and mix until a light, sky-blue shade is achieved. In the third bowl, add more drops of blue gel food coloring (and optionally a tiny touch of green) to create a deeper, ocean-blue hue. Mix thoroughly
- Pour each colored batter into its own prepared cake pan. If you only have two pans, bake two layers first, let them cool slightly, remove, clean and prep a pan for the third, then bake the last layer. Bake for 28-32 minutes, or until a wooden skewer inserted into the center comes out clea
- Let the cake layers cool in their pans on a wire rack for 10-15 minutes. Then, carefully invert them onto the wire rack to cool completely before frosting
- In a large mixing bowl, beat the softened unsalted butter with an electric mixer on medium-high speed for 2-3 minutes, until it’s light and fluffy
- Gradually add the sifted powdered sugar, about 1 cup at a time, beating well after each addition. The mixture will be thick
- Pour in 2-4 tbsp heavy cream (start with 2 tablespoons) and 1 tsp vanilla extract. Add a pinch of salt. Beat on medium speed until the frosting is smooth and creamy. If it’s too thick, add more cream, one teaspoon at a time, until you reach your desired consistency
- Divide the frosting into three bowls. Leave one bowl white. In the second bowl, add light blue gel food coloring. In the third bowl, add a deeper blue (or teal) gel food coloring. Mix each thoroughly
- Once the cake layers are completely cool, use a serrated knife to level any domed tops, creating flat surfaces
- Place your darkest blue cake layer on your serving plate or cake stand. Spread a generous layer of the medium blue frosting evenly over the top
- Carefully place the light blue cake layer on top. Spread another generous layer of the medium blue frosting
- Finally, top with the white cake layer
- Apply a very thin layer of the medium blue frosting over the entire cake (top and sides) to create a "crumb coat" that traps any loose crumbs. Chill the cake in the refrigerator for 15-20 minutes to set the crumb coat
- Apply a thicker, even layer of the medium blue frosting all over the top and sides of the cake. Smooth it with an offset spatula or bench scraper
- For an optional ombre effect, apply stripes of the different colored frostings (darkest blue at the bottom, moving to light blue and then white at the top) around the sides of the cake. Then, use a clean bench scraper to smooth and blend them together for a seamless ombre
- Use a small offset spatula or the back of a spoon to create wave-like textures in the frosting, especially on the top and upper sides
- Generously press your ocean-themed sprinkles onto the sides and top of the cake
- Arrange any edible shells, edible glitter, gummy fish, or other mermaid-themed candies strategically on top of your cake
Notes
Ensure eggs (for homemade cake), butter, and milk are at room temperature for the best cake batter and smoothest frosting.
Avoid overmixing the cake batter to prevent a tough, dry cake. Mix until just combined.
Always opt for gel food coloring for vibrant colors without altering the consistency of your batter or frosting.
Level cooled cake layers using a serrated knife or cake leveling tool for a stable cake.
Do not skip the crumb coat; it's essential for a smooth, crumb-free final frosting layer.
If your kitchen is warm or you're taking your time, chill the cake in the fridge for 10-15 minutes periodically to firm up the frosting.
Use a piping bag fitted with a star or round tip for precise wave effects or adding small details.
Involve kids in decorating, such as adding sprinkles and arranging edible decorations.
Periodically wipe your offset spatula clean when smoothing frosting to achieve a smoother finish.
Feel free to get creative with colors, candies, or edible glitter as this recipe is a guide for your canvas.
To prevent cut cake pieces from drying out, press plastic wrap directly onto the cut surface before covering or refrigerating.
If freezing a whole frosted cake, place it uncovered in the freezer until firm (1-2 hours), then wrap tightly in plastic wrap and aluminum foil. Freeze for up to 1 month.
To thaw a frozen cake, unwrap it and let it sit in the refrigerator overnight. Then, bring it to room temperature for about 1-2 hours before serving.
For the best texture and flavor, let a refrigerated cake sit at room temperature for at least an hour before serving.
- Prep Time: 70 mins
- Cook Time: 30 mins
- Category: Dessert
- Method: Baking
- Cuisine: American
- Diet: Gluten-Free
Nutrition
- Serving Size: 1 serving
- Calories: 450 kcal
- Sugar: 45g
- Sodium: 320mg
- Fat: 20g
- Saturated Fat: 12g
- Unsaturated Fat: 8g
- Trans Fat: 0g
- Carbohydrates: 65g
- Fiber: 0.5g
- Protein: 4g
- Cholesterol: 45mg