30th Classic Car Birthday Cake Recipe

In the 10 years I’ve been with him, I’ve never known Hubs to have a proper birthday cake. He’s one of the lucky or unlucky people (depending on your viewpoint) who arrived on this earth just in time to interrupt Christmas Dinner. As this year was a significant birthday I wanted to make him a special cake. I subtly asked him many months ago as to what his dream cake was and set about making it. His brief was:

“Victoria sponge and chocolate sponge with buttercream and topped with sugarpaste”

In other words a sweet toothed man’s heaven. Not really the ideal cake to eat after a delicious 3 course Christmas dinner, but I wasn’t going to let Hub’s birthday slip by unnoticed. This cake required some serious stelth-like baking. The original plan was to make and decorate the cake while Hubs was at work but a last-minute contract for me meant this wasn’t possible. Anyone who has seen our kitchen/cottage will know there isn’t many places to hide and make secret cakes, so in between Hubs being sent out of the house for hours on end  I was working on the cake. It’s amazing what you can hide in that rarely used wok on top of the cupboards. He knew I was up to something, but didn’t know exactly what.

I decided to theme the cake on the classic car he is currently restoring. Initially was going to use just the Wilton 233 tip to edge the cake and road but I got carried away and decided to decorate the cake with things we may see on our journeys through the countryside in Hub’s classic car. Any metaphors you see on the cake are totally incidental.

The final cake weighed in at 3.5 kg and contained an unholy 1.5kg of white chocolate ganache. Surprisingly given the amount of chocolate the cake wasn’t too sweet. Usually I would have used dark chocolate ganache under the icing, but went for white chocolate ganache as this is Hubs’ favourite and he despises dark chocolate. I’m now converted to using ganache instead of using buttercream under sugarpaste. It’s far nicer to work with, tastes better, but I’ll only use it on special cakes as I’d forgotten how expensive chocolate was until I came to make this cake. Bonus of using ganache is that leftovers can be frozen. This will be transformed into truffles once our Christmas chocolate mountain has been devoured.

The methods I used to make and decorate the cake are a hash of self-taught techniques along with things I’ve learnt from Planet Cake book and Artisan Chocolate course. If you wanted to significantly cut down the time for making this cake use buttercream instead of ganache. Stand by for possibly the longest recipe I’ve ever blogged.  A big thank you to all the family and friends to helped us celebrate Hub’s 30th.

30th Classic Car Birthday Cake Recipe

Makes 1x  20cm cake
Prep Time: 45 mins
Cook Time: 40 mins
Decorating time: 1 hr 30 mins
Total Time: 1 hr 25 mins
Course: sweet
Keyword: Birthday cake
Servings: 15 people


White chocolate ganache

  • 1.3 kg white chocolate grated or finely chopped
  • 450 ml double cream

Plain sponge cake

  • 3 eggs (weigh these in their shells and use equal weight for butter sugar
  • Stork margarine or butter
  • caster sugar
  • self-raising flour
  • 2 tsp vanilla extract

Chocolate sponge cake

  • 3 eggs weigh these in their shells and use equal weight for butter & sugar
  • Stork margarine or butter
  • caster sugar
  • self-raising flour weight of eggs ÷5 then x4 (or egg weight x 0.8 = amount of flour)
  • cocoa powder weight of eggs ÷5 (or egg weight x 0.2 = amount of cocoa)
  • 1 tsp vanilla extract


  • 100 g apricot jam/glaze
  • 100 ml boiling water


  • 1.25 kg green sugarpaste
  • royal icing sugar optional
  • Other sugarpaste for decoration


  • 8 inch cake board
  • 10 inch cake board
  • pallet knife
  • cake turntable if you don’t have one use smaller cake tin or similar to help raise your cake from the work surface


  • The ganache needs to be made first as it needs to cool and set overnight before being applied to the cake. In a heavy based saucepan heat the cream until it is at boiling point.
  • Put half the chocolate in a large bowl and pour over the hot cream. Whisk with a hand whisk until mixture is smooth. Add the remaining chocolate a handful at a time and keep whisking to melt the lumps. Allow to cool completely and set overnight.
  • Line the bottom of two 20cm cake tins with baking parchment. Pre heat oven to 180°c.
  • First make the vanilla sponge. Beat the butter and sugar together until fluffy then beat in the eggs one at a time until well combined. Before adding the third egg add a spoonful of the flour into the mix to help stop the mixture curdling.
  • Stir in the vanilla extract then fold in the flour. It needs to be of dropping consistency (in other words it drops off the spoon easily). If not, add a small amount of milk to help loosen the batter. Split the mixture equally into two bowls.
  • Now make the chocolate sponge. Beat the butter and sugar together until fluffy then beat in the eggs one at a time until well combined. Before adding the third egg add a spoonful of the flour into the mix to help stop the mixture curdling.
  • Stir in the vanilla extract then fold in the flour and cocoa. Add milk if needed to get it to dropping consistency. Share the mixture equally between another two bowls.
  • Take one bowl of the vanilla cake mix and one of the chocolate mixture. Blob the mixture one spoon at a time into one of the cake tins then swirl the mixture a small amount with a skewer. Repeat with the other mixture in the remaining cake tin.
  • Bake for around 40 minutes until the cakes have risen and a skewer comes of out the cakes clean.
  • Let the cake for rest for a few minutes before turning it out of the tin and removing the baking paper. Allow to cool on a wire rack.
  • Blast the ganache for 10 seconds or so in the microwave to make it easier to spread. Don’t overheat the ganache or will burn.
  • Put a small amount of the ganache on the 8 inch cake board and stick one of the cakes to the board. If need be trim the top of the cake to make it flat. Brush with some of the syrup to help keep cake moist.
  • Spread some of the ganache on the top of the bottom cake and place the next cake on top. Again trim the cake to make it flat and brush with syrup.
  • With a pallet knife begin to build up the ganache on the side of the cake until it is in line with the edge of the board. Then spread the ganache onto the top of the cake. Let it set overnight.
  • If you want a defined edge on the ganache once the cake has set overnight take a long pallet knife, dip in boiling water and glide across the cake to smooth the ganache. Allow the cake to set again overnight.
  • Make a paste of royal icing and put a large blob of this in the center of the 10 inch cake board then place the cake on the smaller board in the middle.
  • Knead the sugarpaste until it is soft then roll out on a piece of baking parchment or worksurface lightly dusted with icing sugar until big enough to cover cake. Use the palm of your hand to buff the icing and give it a shine.
  • Brush the cake with some of the remaining syrup then transfer the sugarpaste across to the cake. Smooth the icing on the top of the cake then work your way down the sides gently working the icing down to stop creases. Carry the icing on along the board to cover it then trim with a sharp knife. Buff the icing again with your hand and/or plastic smoother.
  • Adorn the cake with sugarpaste decoration. Use gin or vodka to stick the decorations on as it is sticker and less likely to stain the sugarpaste.

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