This is the cake to end all birthday cakes. Not just a mint choc chip cake, but a mint choc chip cake with added oreos! I first planned to make this cake without them, but when I tasted the mint oreos I knew I had to find a way to include them in this recipe. It’ll take a good few hours to put the elements all together but it is SO worth it.
You’ll end up with an 8 layer cake – 4 mint and 4 chocolate – sandwiched with alternating layers of chocolate and mint choc chip buttercream, coated in mint Oreo buttercream, topped with a chocolate ganache then decorated with mint Oreos and other assorted chocolates. Phew!!!
Let’s start with the chocolate sponge. This cake is a bit like a mudcake, nice and fudgy, and holds up well in a layer cake without tasting dry. You’ll need:
- 350g plain flour
- 65g cocoa powder
- 370g caster sugar
- 1 teaspoon bicarb
- 1/2 teaspoon salt
- 240ml cooled coffee
- 240ml buttermilk
- 210ml veg oil
- 3 eggs
Preheat your oven to 170 C and line 2 8 inch cake tins.
Mix the dry ingredients together in a large bowl. Whisk all the wet ingredients together in a separate bowl and pour into the flour mixture. Keep whisking until everything is well combined – you should have a fairly runny mixture. Divide it evenly between the two tins and bake for about 25 minutes, or until a skewer comes out clean.
Next, let’s tackle the mint sponge. You’ll need:
- 250g butter/Stork
- 250g caster sugar
- 4 eggs
- 350g self raising flour
- 1 teaspoon peppermint extract
- 3 tablespoons milk
- green gel food colouring
This is a traditional sponge recipe. You’ll need to keep the oven at 170 C and line two 8 inch tins.
Put the butter and sugar in a bowl and beat together for at least five minutes, either with a hand held whisk or a free standing mixer. You want it to get very pale and fluffy as it will make the sponge super light. Add the eggs one at a time with a tablespoon of flour, mixing well after each one. Add the rest of the flour and fold through, don’t beat too much at this stage. In a separate bowl mix together the milk, peppermint and gel colour. You will only need a few drops to get a nice minty colour. Whisk this into the cake mixture and have a taste – if you think it could do with a bit more mint, add a little more peppermint extract. Divide evenly between the tins and bake for about 25 minutes, or until a skewer comes out clean.
When it comes to building a cake this tall you need all the layers to be really even otherwise it’s a bit of a nightmare to get it nice and straight! I found buying a cake leveling wire really helped me as I wasn’t too great at slicing cakes just with a knife. You can pick one up for a few pounds in Lakeland or larger supermarkets.
Wait until the cakes are stone cold before cutting – they’ll crumble apart otherwise. Using the wire or knife, cut the tops off the cakes so they are flat, then cut them in half. You should have 4 chocolate and 4 mint layers. Now it’s icing time! You’ll need to make the mint and chocolate buttercreams before you start building.
For the chocolate buttercream:
- 90 dark chocolate
- 150g unsalted butter
- 270g icing sugar
- 2 tablespoons milk
Start by melting the chocolate, either gradually in a microwave or in a bowl set over a pan of simmering water. Set it aside to cool while you make the buttercream. Beat the butter in a bowl with a hand mixer or freestanding one for a good five minutes or so – you want it to go almost white. Add the icing sugar in two stages, mixing well after both. Add the milk and beat for another 5 minutes until nice and fluffy. Finally pour in the melted chocolate and mix until totally combined and all chocolatey.
For the mint buttercream you’ll need:
- 150g unsalted butter
- 340g icing sugar
- 2 tablespoons milk
- 1 teaspoon peppermint extract
- green gel colouring
- 100g dark chocolate chips
Just like the chocolate buttercream, you need to beat the butter for 5 minutes to get it all pale and fluffy. Add the icing sugar in two stages, beating well after each. Mix the milk, peppermint, and a couple of drops of food colouring together and add to the icing. Have a taste and if it’s not minty enough add some more peppermint extract. Add more colouring if it’s not green enough yet too.
Now it’s time to get building! Take a cake board or stand and put a small spoonful of one of the buttercreams on it to secure the cake. Start by placing a chocolate cake layer on the board, then add a generous dollop of mint buttercream on top. Smooth it out with a palette knife and scatter over a handful of choc chips. Top with a mint cake layer and spread over a dollop of chocolate buttercream. Continue with all your alternating layers until you have a lovely big cake. You’ll have some buttercream and choc chips left over, but that’s ok, they can be used for the decoration.
The cake is still naked at this point so we need the mint Oreo buttercream to cover it. I got my mint Oreos from the foreign foods isle at Tesco, but they’re quite expensive so you could just use normal Oreos as a substitute if you want. You’ll need:
- 300g unsalted butter
- 675g icing sugar
- 2 teaspoons peppermint extract
- 4 tablespoons milk
- 100g mint Oreos
- green gel colour
For the third and final time, beat the butter until pale and fluffy. (You’ll be a pro by now!) Add the icing sugar in two stages and whisk until incorporated. Mix together the milk, peppermint and green colouring and add to the icing. Using a food processor, or a bag and a rolling pin, blitz the Oreos into tiny crumbs and fold through the buttercream. You shoud have a nice big bowl of lovely light, minty, Oreoy buttercream.
I start my cakes with a crumb coat – it makes it much easier to get a smooth finish. So using a small amount of buttercream, coat the cake. Don’t worry if any crumbs come away, it’s better they do so now rather than at the end! Stick the cake in the fridge for about an hour to let the crumb coat harden.
Once the cake’s solid, use the rest of the buttercream to coat it with a nice even layer. I used a long cake ruler to get a smooth finish, but you could use a palette knife.
Now, while the cake looks and smells totally yum, it’s still a little bare. So I thought I’d top it with a chocolate ganache drip. Pop the cake back in the fridge to firm up while you make it.
- 100g dark chocolate, chopped
- 125ml pot of double cream
Heat the cream gently in a saucepan until small bubbles start to form, then pour it over the chopped chocolate in a bowl. Leave it for five minutes so the chocolate can melt, then beat together until it’s all smooth and glossy.
You want it to still be runny when you pour it on the cake so it can start to drip down the sides, so acting fairly quickly, take the cake out the fridge. Pour the ganache on to the top, and using a palette knife gently coax it towards the sides so it tips over the edge. Once you’ve got the effect you want, stick the cake back in the fridge so the ganache can set.
Congratulations if you’ve made it this far!! We are almost done – I promise. This last section is all about the decoration so that’s pretty much up to you and the effect you want. Gather together anything you fancy to make it look spectacular. I used:
- a couple of leftover mint Oreos
- some left over choc chips
- the remaining chocolate and mint buttercreams
- mint aero bubbles
- mint M&Ms
Scatter the decorations on top how you like. I put the buttercreams in piping bags and dotted it on in a crescent shape to make it easier to stick on the chocolate decorations.
And now FINALLY we are done! What you have is a delicious, light cake that tastes chocolatey, Oreoy (totally a word!) and minty, and with a little bit of texture from the choc chips. It’s a bit of a show stopper, inside and out – look at all those defined layers! Mint choc chip is a bit of an underrated combination when it comes to cakes, but hopefully the addition of Oreos puts it in its rightful place.