How to Make a Birthday Cake Soap That Smells Like Cake

8–9″ silicone cake pan (smaller pan = taller cake)
About 6 lb. melt-and-pour soap base (see note below)
Pink soap dye
Cupcake fragrance oil
Liquid dish soap
Ziplock or piping bag and a star piping tip
Spray bottle with 99% isopropyl alcohol (or rubbing alcohol in a small spray bottle)
Large microwave-safe bowl
Large kitchen knife (very sharp)
Hand mixer
Sprinkles for decoration

Note: I used a scored soap base because it was easy to measure. A 5 lb. base is more cost-effective but will produce slightly thinner layers; you can estimate measurements accordingly.

Please read all steps before starting. Melt-and-pour soap sets quickly, so preparation and speed help achieve clean layers.

1. For the first cake layer, cut six scored columns of soap base (about 1.5 lbs) and chop into cubes.
2. Melt the cubes in the microwave at 30-second intervals, stirring between intervals until fully melted.
3. Stir in 1/2 teaspoon of fragrance oil (do not add dye at this stage).
4. Pour the melted soap into the bottom of the silicone pan. Place the pan on a level surface where it can remain undisturbed. Lightly spray the top with isopropyl alcohol to remove air bubbles.
5. For the first frosting layer, melt four columns of soap base using 30-second intervals. Add a few drops of pink soap dye and stir to color—add more if needed. Work quickly so the soap remains pourable.
6. Pour this colored layer on top of the set white layer and spray lightly with alcohol to eliminate bubbles.
7. Repeat the white cake layer and another colored frosting layer, spraying each layer with alcohol after pouring.
8. Allow the full cake to cool and set completely. When set, carefully peel the silicone pan away from the soap cake.
9. Using a very sharp knife, score the cake circle into eight equal sections and cut through the layers in a single smooth motion for clean edges.
10. To make the frosting dollops, follow a 4 oz soap to 2 tbsp liquid dish soap ratio. For the topping you’ll need about 8 oz (four columns) of soap base—cut into cubes.
11. Melt the cubes at 30-second intervals until fully liquid, then add 4 tablespoons of liquid dish soap.
12. Use a hand mixer to whip the mixture until it forms very stiff peaks, creating a frosting-like texture.
13. Transfer the whipped soap into a piping or ziplock bag fitted with a star tip and pipe dollops onto each cake slice.
14. Immediately add sprinkles or a small candle for decoration, then let the frosting set completely before handling.