Best Mermaid Petal Cake
By Chef Sarah Chen
April 29, 2026
90 min
Serves 20
This mermaid-inspired cake is easy to make at home.
Ingredients
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- 1 box vanilla cake mix, plus ingredients called for on box
- 1 1/2 c. butter, softened
- 6 c. powdered sugar
- 2 tsp. pure vanilla extract
- 6 tbsp. heavy cream
- 1 tsp. purple gel food coloring
- 1 tsp. Blue gel food coloring
- 1 tsp. teal gel food coloring
Instructions
Step 1
Preheat oven to 350°. Line two 8” round cake pans with parchment paper and grease with cooking spray.
Step 2
Prepare cake mix according to package instructions.
Step 3
Divide cake batter between prepared pans and bake according to package instructions.
Step 4
Let cakes cool in pans for 10 minutes, then invert onto wire racks to cool completely.
Step 5
Make frosting: In a large bowl using a hand mixer, beat butter and half of the powdered sugar until smooth. Add the remaining powdered sugar, vanilla and 4 tablespoons heavy cream and beat until fluffy. If the mixture is too stiff, add more heavy cream.
Step 6
Place a dab of frosting on cake plate (to keep cake in place) and place parchment strips on each side of the cake plate. Place down first cake and top with frosting, then top with second cake and frost with a thin crumb coat of frosting.
Step 7
Divide remaining frosting into three small bowls and stir one shade of gel food coloring into each bowl of frosting.
Step 8
Place each color of frosting into its own piping bag fitted with a large round piping tip.
Step 9
Starting at the top of one side of the cake, pipe a small circle of purple frosting. Directly underneath the purple frosting circle, pipe a small circle of blue frosting, following by a circle of teal frosting underneath. Continue in a vertical line in the same order of colors until you run out of space on the cake.
Step 10
Using an offset spatula, smear each circle of frosting horizontally across the side of the cake about 1 inch. Note: Use a different spatula for each color of frosting to avoid mixing the shades.
Step 11
Repeats steps 9 and 10, slightly overlapping the circles of frosting with the smeared frosting to create a mermaid-scale effect until you run out of space on the side of the cake.
Step 12
Repeat the same circle and smear technique with the frosting on top of the cake, but in concentric circles this time.
Cook's Tips
- Read the entire recipe through before starting.
- Mise en place — measure and prep all ingredients before turning on the heat.
- Use a kitchen scale for baking; volume measurements vary by 10-20%.
- Taste as you go and adjust seasoning at the end.
- Rest cooked proteins before slicing to retain juices.
Common Mistakes (and How to Fix Them)
- Mistake: Crowding the pan. Fix: Cook in batches if needed — steam is the enemy of browning.
- Mistake: Skipping the rest step. Fix: Even 5 minutes of resting redistributes juices in proteins and lets sauces thicken.
- Mistake: Using cold ingredients. Fix: Bring eggs, butter, and dairy to room temperature 30 minutes before starting baking recipes.
Variations
- Add fresh herbs at the end for brightness.
- Swap the protein for a similar one — adjust cook time accordingly.
- Add a pinch of red pepper flakes for heat.
- Use whole grains for a nuttier, more nutritious version.
What to Serve With This
- A simple green salad with lemon vinaigrette
- Crusty bread or warm flatbread
- Roasted seasonal vegetables
- A glass of dry white wine or sparkling water with lime
Storage & Reheating
Cool leftovers within 2 hours. Store in an airtight container in the fridge up to 3-4 days. Freeze for up to 2 months in freezer-safe containers; thaw overnight in the fridge before reheating. Reheat gently in a covered pan over low heat with a splash of water or stock to revive — microwaving on high tends to dry things out.
Nutrition (per serving)
Estimated. Actual values depend on brands and exact measurements.
Frequently Asked Questions
Can I substitute the 1 box vanilla cake mix in this recipe?
You can swap with similar ingredients of comparable texture and moisture. Adjust seasoning to taste — substitutions often need a small bump in salt or acid to compensate.
Why didn't my mermaid petal cake turn out right?
The most common issues are oven temperature variance, ingredient temperature (cold eggs and butter behave differently than room temp), and overcooking. Use a thermometer for protein-based recipes and trust visual/sensory cues over rigid timing.
Can I make this ahead of time?
Most components can be prepped 1-2 days ahead and stored covered in the fridge. For best texture, finish and serve fresh. See storage notes below for specifics.
How do I know when it's done?
Trust visual and sensory cues — color, texture, smell, and internal temperature for proteins (165°F / 74°C for chicken, 145°F / 63°C for fish). Timing in any recipe is a guideline; your equipment varies.
How long does mermaid petal cake last in the fridge?
Stored in an airtight container, leftovers keep 3-4 days in the fridge. Reheat gently to preserve texture — low and slow beats microwave-blasting every time.
Is mermaid petal cake healthy?
Per serving: roughly 7689 calories. Like most recipes, healthiness depends on portion size and what you eat alongside. The healthy version on this site offers lighter swaps if that's your goal.
What should I serve with mermaid petal cake?
Pair with a bright salad, a starch (rice, bread, or potatoes), or roasted vegetables to round out the meal. A simple acidic side cuts richness in heavier dishes.
Can I make this without specialized equipment?
Yes — most recipes can be adapted with standard pots, pans, and a sharp knife. If a specific tool is called for (stand mixer, food processor), there's usually a manual workaround that takes a few extra minutes.
How do I scale this for 40 people?
Doubling works cleanly for most ingredients but not always for time and salt — increase cook time by 20-30%, taste-correct salt at the end. Tripling often needs splitting into two batches for even cooking.
Is this American dish authentic?
This version captures the core technique and flavor profile of traditional American cooking. Regional variations exist — different households and regions add their own twists, all valid.