Step 1

Pre-heat oven to 180°C / 160°C fan assisted oven / gas mark 4 and line and grease 2 x 8 inch round cake tins.

Step 2

Melt the chocolate in a bain marie, or a glass bowl set over a pan of boiling water, then set aside.

Step 3

Pour the milk into a jug and stir in the apple cider vinegar. Let stand for 5-10 minutes to curdle slightly.

Step 4

In a large mixing bowl, or stand mixer, whisk together the flours and starches, cocoa powder, espresso powder, bicarbonate of soda and salt until well mixed.

Step 5

In a separate bowl mix together the vinegar milk, sugars, olive oil, eggs and vanilla then beat into the flour mixture.

Step 6

Finally mix in the melted chocolate until completely incorporated.

Step 7

Divide the mixture between the 2 cake tins and bake in the oven for 35 minutes or until an inserted skewer is removed without a wet crumb.

Step 8

Turn out the cakes and cool on wire racks before filling with buttercream.

Step 9

Melt the chocolate in a bain marie or a glass bowl set over a pan of boiling water, then set aside to cool.

Step 10

Beat butter together with the icing sugar in a stand mixer for at least 6 minutes until light and creamy, scraping down the sides every so often.

Step 11

Add the cocoa powder, melted chocolate and salt then beat until smooth and incredibly creamy.