Astrology Cake

Some cakes are fun. Some are pretty. And then… some just feel like they’ve got a little magic in them. That’s exactly what I felt the first time I made an astrology cake.

I wanted something more than just layers and frosting. I wanted the stars. The moon. That deep, inky night-sky color that makes gold pop like fire.

I didn’t want it to just look good—I wanted it to mean something. Something cosmic. Something bold.

So I sketched a crescent moon with a calm little face, traced constellations with edible gold, and topped it all off with soft swirls of dark blue buttercream.

This cake isn’t complicated. But it is special. Every detail matters—from the smooth navy sides to the tiniest golden star.

And I’m going to walk you through each step like I would with a friend, because if you’re going to put your time into a cake like this, it deserves to be just right.

Table of Contents

Astrology Cake Recipe

Ingredients

For the Midnight Vanilla Cake (3 layers, 6-inch rounds):

2 ¾ cups all-purpose flour (sifted)
2 ½ tsp baking powder
½ tsp baking soda
¾ tsp salt
1 cup unsalted butter (softened)
1 ¾ cups granulated sugar
4 large eggs (room temperature)
1 tbsp pure vanilla extract
¾ cup whole milk (room temperature)
½ cup full-fat sour cream
Deep navy gel food coloring (use sparingly)

For the Navy Swiss Meringue Buttercream (smooth finish & piping):

6 large egg whites
1 ½ cups granulated sugar
2 cups unsalted butter (room temperature, cubed)
2 tsp vanilla extract
Navy blue gel food coloring
Optional: ¼ tsp lemon juice (to stabilize meringue)

For the Gold Decorations:

Fondant (white, about 200g)
Edible gold dust
Clear alcohol or lemon extract (for mixing gold paint)
Small paintbrush (food-safe)
Constellation template printouts (optional)
Crescent moon & sun cookie cutters or hand-sculpted fondant shapes
Edible gold pearls (for star centers and piping tops)
Fine edible glitter or shimmer dust (gold or white)

Instructions

1. Bake the Cake Layers:

Preheat oven to 350°F (175°C). Grease and line three 6-inch cake pans with parchment paper.
In a bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
In a stand mixer, beat butter and sugar on medium-high speed until fluffy (about 3–4 minutes).
Add eggs one at a time, beating well between each addition. Add vanilla.
Mix milk and sour cream together. Alternate adding dry ingredients and milk mixture to the butter mixture in three parts, starting and ending with the dry.
Add a few drops of navy blue gel coloring to get a rich dark blue shade. Mix gently until the batter is evenly colored—don’t overmix.
Divide batter evenly between the three pans and bake for 28–32 minutes. Cakes should spring back lightly and a toothpick should come out clean.
Cool in pans for 10 minutes, then turn out onto racks and cool completely.

2. Make the Navy Swiss Meringue Buttercream:

In a heatproof bowl over a pot of simmering water (double boiler), whisk egg whites and sugar constantly until the sugar dissolves (about 160°F or warm and smooth to the touch).
Transfer to a stand mixer and whip on high speed until glossy stiff peaks form and the bowl feels cool (10–12 minutes).
Switch to paddle attachment and add butter gradually, a few cubes at a time, while mixing on medium. If it curdles, keep beating—it will come together.
Add vanilla and navy blue gel food coloring until a deep, rich blue tone is achieved. Beat until silky smooth.

3. Assemble the Cake:

Level cake layers if needed. Place the first cake layer on a cake board or turntable.
Spread a layer of buttercream, stack the next layer, repeat, then top with the final cake round.
Apply a thin crumb coat all around and chill for 20 minutes.
Once chilled, apply a smooth final coat of buttercream with an offset spatula. Use a cake scraper for sharp edges. Chill again.

4. Create Celestial Decorations:

Roll out white fondant to ⅛ inch thickness.
Use moon, sun, and star cutters (or shape by hand using small tools or a stencil and X-Acto knife).
For constellations, create tiny fondant dots for stars and roll thin fondant lines or draw the lines later.
Mix edible gold dust with a few drops of clear alcohol or lemon extract to make gold paint. Carefully paint all the fondant decorations gold. Let dry for 10–15 minutes.
Use a clean brush to apply edible glitter across some fondant pieces for shimmer.

5. Apply the Constellations & Accents:

Use a tiny dab of buttercream to attach the moon, sun, stars, and constellation pieces around the cake sides. Arrange carefully and symmetrically.
Use a toothpick or edible marker to sketch faint constellation lines before piping or applying fondant strings.
Lightly splatter edible gold paint across the cake using a stiff brush for the starry sky effect (cover your workspace).
Pipe tall swirls of navy buttercream on top using a large open star tip. Place gold pearls in the center of each swirl.
Dust entire cake lightly with edible shimmer for a magical celestial glow.

Final Touches:

Chill cake for 30 minutes before serving to firm up the decorations.
Serve at room temperature for best texture and flavor.

How Do I Decorate a Cake With Zodiac Signs?

Decorating a cake with zodiac signs can be simple if you break it into small steps. Focus on using symbols, shapes, and colors that match the astrology theme.

Use edible gold paint: Draw constellation lines and zodiac symbols directly on the buttercream or fondant surface.
Cut out fondant shapes: Create star signs, moons, suns, and planets using small cutters or a stencil and sharp knife.
Add shimmer or galaxy colors: Blend deep blue, purple, and black shades in your frosting for a galaxy effect.
Use small star piping tips: Pipe stars using stiff frosting to fill the background or border.
Add edible pearls or sugar balls: These work great as tiny stars in your night sky layout.
Label each sign clearly: If you’re making a full zodiac set, place each sign’s name or symbol near its constellation.

Which Tools Do I Need To Make An Astrology-Themed Cake?

You don’t need fancy tools, just a few basics that help shape, paint, and design the cake smoothly.

Round cake pans: For even baking and stacked layers.
Offset spatula & cake scraper: To smooth out frosting for a clean base.
Food-safe paintbrushes: For applying gold dust and drawing designs.
Star and moon cutters: To shape fondant or gum paste easily.
Piping bags with small round tips: Great for piping dots, stars, and borders.
Gel food coloring: Needed to create deep galaxy tones.
Tweezers or toothpicks: For placing tiny edible stars or making constellation lines.
Edible markers: Can help sketch outlines before painting or piping.

Can I Make An Astrology Cake Without Fondant?

Yes, absolutely. You can get beautiful results using just buttercream and a few creative tricks.

Use buttercream for your base and piping: Smooth navy buttercream makes a great galaxy background.
Draw directly with edible paint or markers: You can skip fondant and still create detailed zodiac signs.
Piped decorations work well: Stars, moons, and borders can all be piped using stiff frosting.
Use gold leaf or shimmer spray: These give a metallic look without needing fondant shapes.
Add edible pearls or shaped candies: Use them for planets or star clusters without needing to mold anything.

Is An Astrology Cake Good For a Birthday Party?

Yes, it’s a fun and thoughtful choice for birthdays, especially for someone into horoscopes or space-themed designs.

It’s personal: You can match the design to their zodiac sign or birth constellation.
It’s bold and unique: The galaxy theme stands out more than a regular birthday cake.
Easy to customize: You can make it bright and colorful or go for a dark, elegant space look.
Works for all ages: Kids, teens, and adults all enjoy the cosmic design.