225ml| 8oz buttermilk or milk soured with 1 tsp lemon juice
100ml| 4fl oz vegetable oil
1tspvanilla extract
For the caramel
150g| 2/3 cupcaster sugar
30ml| 1/8 cup water
100ml| 3.4 fl oz double cream
30g| 2 tbsp unsalted butter
2tbspIrish whiskey
Pinchcoarse sea salt
Ermine frosting
200g| 7oz unsalted butter
200g| 7oz sugar
235ml| 1 cup semi-skimmed milk
5tbspplain flour
pinchsalt
seeds from 1 vanilla pod
Instructions
Make the caramel. Half fill a frying pan with cold water and keep it handy. Put the double cream and butter in a small measuring jug and microwave for 30 seconds or until the butter melts. Set aside.
Put the sugar and water in a medium heavy-bottomed pan. Bring to the boil and cook, swirling the pan, until you have a golden caramel – this will take several minutes.
Remove the caramel from the heat and pour in the cream/butter - be careful, this will cause the caramel to bubble and rise in the pan. Plunge the bottom of the pot in the frying pan to stop the caramel from cooking further. The caramel may seize and curdle – don't worry!
Add the salt and whiskey and return the saucepan to the stove and cook the caramel for 2-3 minutes over medium-low heat, whisking continuously until the caramel is smooth.
Strain the caramel through a fine sieve into a jar and cool in the fridge before using. Caramel will keep in a sterilised jar in the fridge for several weeks.
Make the frosting. Put the milk and flour in a small saucepan and whisk over medium-low heat until the mixture thickens and the whisk leaves a trail. Transfer to a bowl and cover with cling film, pressing it on the surface to prevent a skin forming. Cool completely before using (speed up the process by putting the bowl in the fridge or freezer).
Whisk the butter and sugar together for several minutes, stopping the mixer and scraping the sides and bottom of the bowl as you go. Add the vanilla and salt and whisk in.
Start adding the milk roux, one tablespoon at a time, until the frosting is completely smooth and has the consistency of whipped cream.
Preheat the oven to 180C (350F). Prepare 3x20cm pans or 2x23cm pans – grease and line the bottoms and sides with baking paper.
Sift the flour, sugar, cocoa powder, soda, baking powder and salt together into a large bowl.
Put the eggs, Guinness, buttermilk, oil and vanilla extract into the bowl of your stand mixer and whisk together on low speed until combined.
Gradually add the dry ingredients and beat for a couple of minutes, scraping the bottom and sides of the bowl. The batter will be fairly thin.
Pour into the cake tins filling only halfway. Bake the 20cm cake layers for about 20-25 minutes (the 23cm cakes take 30-35 minutes) or until the top of the cake is firm and a skewer inserted in the centre comes out clean. Cool on a wire rack.
Pipe or spread the frosting over the layers drizzling caramel over each layer before sandwiching together. Pipe frosting over the top layer and drizzle with caramel. Serve at room temperature (the frosting will harden in the fridge).
Notes
I used my Wilton Easy Layer Cake Pans (affiliate link) to create the cake in the photos. The pans are only 15cm (6in) and fairly shallow – you get as many as 8-9 small layers with this amount of batter. These need about 15-20 minutes in the oven – watch they don't burn!