How To Make a Geode Cake

How To Make a Geode Cake

Purple Geode Cake frosted to look like a galaxy with a carved indent filled with purple and pink rock candy and silver leaf edging

A geode cake is not for the faint-hearted. Let me just put it out there straight away. It’s basically a large, layered and frosted cake with a cavity sliced out of it and then filled with various sizes of rock candy. If you’re looking for a quick and easy way to decorate a  cake, this isn’t it. But I’ve got plenty ideas here and here. If you’re up for a challenge though, and want some serious wow-factor? Make this baby! I’ve said numerous times I’d never make a geode cake, but when one of your best friends turns 50 and has a mild obsession with quartz and crystals, then well, you put aside your issues and make it happen! It also may have something to do with with the fact that I didn’t tackle it alone, I joined forces with my cake partner in crime Love Life Cupcakes. Here’s how we did it:

Purple Geode Cake frosted to look like a galaxy with a carved indent filled with purple and pink rock candy and silver leaf edging

WHAT YOU’LL NEED:

5 x 25cm vanilla cake layers (I used this recipe)

2 x 15cm vanilla cake layers

1 x quantity vanilla buttercream 

Purple food colouring gel

Fushia food colouring gel

Black, purple, pink and silver rock candy sugar swizzle sticks (available here)

Silver leaf (or silver glitter)

Black dusting glitter

Close up of the purple geode cake with rock candy sugar crystals and silver leaf

STEP 1: Partially freeze your cake layers (on a level surface) before you begin assembling the cake (about an hour before should be sufficient). If the cake is very cold, the buttercream will set quite quickly which will make assembling ALOT easier and your cake won’t end up being the leaning tower of Pisa.

STEP 2: Tint 2/3 of the buttercream a light purple colour and start assembling the cake layers, alternating with buttercream. Check out this video post if you want to see how. Coat the entire cake with a thin layer of frosting then refrigerate to set and finish off with a final layer.

STEP 3:  Using a sharp bread knife, cut a cavity out of the cake to create an indent.

STEP 4: Half the remaining buttercream and tint half a deep purple and the other half a dark pink. Cover the cavity with the dark purple buttercream and place a few blobs around the front of the cake. Place blobs of pink frosting in between then using a palette knife smooth the buttercream so the colours blend into each other forming a galaxy/watercolour effect.

STEP 5: Cut the bottom of the swizzle sticks off, then starting from the centre of the indent, stick 3-4 black crystal sticks into the centre of the cake. Stick the purple ones around it. Crush the remaining purple sticks and place the crystals around finishing with a layer of pink and then silver. Dust the centre with black glitter.

STEP 6: Using tweezers, carefully place a line of silverleaf around the edges. If you want, decorate the cake with white chocolate sails dusted with edible silver dust.

Purple Geode Cake frosted to look like a galaxy with a carved indent filled with purple and pink rock candy and silver leaf edging