Step 1

Mix the instant coffee and boiling water to a paste and leave to cool.

Step 2

Preheat the oven to 180ºC (fan) / 350ºF / Gas Mark Grease and line two 23cm / 9 inch cake tins with a circle of baking parchment or greaseproof paper.

Step 3

Roughly chop the walnuts and set aside.

Step 4

In a large bowl, combine the dry ingredients (flour, caster sugar and baking powder).

Step 5

In a jug, mix the wet ingredients (milk, oil and cooled coffee mixture), then add these to the dry ingredients.  Mix until smooth.

Step 6

Stir through the chopped walnuts, then divide the mixture evenly between the two tins.  Tap each tin firmly on the work surface to remove small bubbles, then bake for 18-22 minutes until an inserted skewer or knife comes out clean.

Step 7

Leave to cool in the tin for a few minutes, then turn out onto a wire rack, remove the baking parchment and leave to cool completely.  Ideally, it is best to leave the fully cooled cakes in an airtight tin or container overnight, to layer with buttercream the following day, (this helps the cakes to soften and stops a crust forming), but if you don't have time, just make sure they are completely cool throughout before starting to layer and decorate them.

Step 8

Mix the instant coffee and boiling water to a paste and leave to cool.

Step 9

In a food mixer or large bowl with electric whisk/mixer, mix the dairy-free margarine and icing sugar until fully combined, then add the coffee mixture, salt and cream, and whisk until light and fluffy.

Step 10

Spread about a third of the buttercream over the bottom layer of the cake.  Put the top layer in place and spread half the remaining buttercream over the top.  Pipe the remaining buttercream in small rosettes around the edge of the cake.

Step 11

Finely chop the walnuts and scatter over the cake.