Collect together your equipment (see Recipe Notes below) and ingredients.

Preheat oven to fan 160°C/180°C/350°F/Gas 4 and line a 20cm/8inch square tin with greaseproof paper.

Make the coffee slice: dissolve the coffee powder in the boiling water and set aside to cool.

It is important that the butter is at room temperature and soft enough to beat. If it is a little hard, beat it with a whisk before adding the other ingredients. If it is already quite soft, you do not need to do this. For information on softening butter, see here.

Measure all the remaining ingredients, apart from the coffee, into the mixing bowl with the butter. I place my mixing bowl on top my scales and weigh everything in directly. Add the coffee at the end, when it has cooled a little.

Use an electric whisk to beat until combined. This should take less than a minute. Half way, use a spatula to scrape the sides of the bowl and ensure even mixing.

Tip into your lined baking tin and level the surface, ensuring the cake goes into all the corners.

Bake in the centre of a preheated oven for 40 – 50 minutes until cooked. It is cooked when:

– the centre feels springy when lightly touched with your finger and no imprint remains.

– a toothpick inserted into the centre of the cake comes out clean.

– the cake is beginning to come away from the sides of the tin.

Now make the drizzle: make up your chosen strong coffee and set aside to cool. I use 2 Nespresso capsules.

Weigh the sugar into a mixing bowl and add the cooled coffee and Bailey”s Irish Cream. Stir well to mix.

As soon as the cake comes out of the oven, spoon the drizzle evenly over the top and leave the cake to cool in the tin for 30 minutes.

Using the baking parchment overhang, remove the cake from the tin onto a wire rack and leave until completely cool.

If desired, sprinkle over a little extra granulated sugar and then slice into 12 or 16 squares.