Preheat the oven to 180C (160C fan forced) / 350F.

If you haven't already, mix the coffee granules with boiling water.

Grease 3 round 8-inch sandwich tins (cake pans). Dust all over with cocoa, tapping out the excess.

In a very large bowl, sift the flour, cocoa powder, baking soda and baking powder together. Add the sugar and salt and use a balloon whisk to gently whisk it all together.

Make a well in the centre of the dry ingredients and add the wet ingredients – coffee, oil, buttermilk, eggs and vanilla. Use a spatula to give it a rough mix, then swap to an electric mixer and beat for 1 minute.

Evenly divide the batter between the prepared pans.

Bake for 30-35 minutes, turning the pans at about the 20 minute mark, until a toothpick comes out with just sticky crumbs attached.

As soon as the cakes come out of the oven, using another cake pan the same size or just a glass to gently push down the dome on the cake.

After 5 minutes, turn the cakes out onto a wire rack to cool completely.

In the bowl of a stand mixer with a paddle attachment, beat the butter and ½ cup of the icing sugar on medium speed for 5-6 minutes.

Add the vanilla, salt and half of the remaining sugar and beat on low until combined. With the mixer on low, spoon in the remaining sugar. Scrape down the sides of the bowl. Beat for a further 2 minutes at medium speed.

Add the cream and beat for a final 2 minutes at medium speed until it looks light, thick and whipped.

Start by placing 1 of the layers of cooled cake onto a cake platter, flat side down. Spread about ¾ cup of the frosting over the top. Repeat this same step with a second layer of cake and frosting.

Place the final cake layer on top, flat side up. Spread the remaining buttercream over the top and sides.