Preheat your oven to 180ºc/160ºfan, and line a 2lb loaf tin!
In a microwave proof bowl, add the chocolate and butter and heat and mix until melted.
Add the coffee granules to a mug, and pour over the boiling water and mix until smooth - add the coffee mix into the chocolate and mix until smooth.
In a separate bowl, add the flour, cocoa powder, baking powder, bicarbonate of soda and sugar to a large bowl and whisk until distributed.
In another bowl, mix together the baileys and lemon juice, and eggs.
Add the three mixes together - I pour the chocolate/coffee mix and the egg/baileys and lemon juice mix into the dry ingredients and fold until smooth. You do not need to use a stand mixer as you may over-mix it.
Pour the mixture into the lined 2lb loaf tin - bake in the oven for 55-60 minutes, or until baked through!
Leave to cool fully once baked!
Frosting
Make sure your butter is at room temperature!
Beat the butter on it's own for a few minutes to soften!
Add in the icing sugar and cocoa powder 1/2 at a time, and beat until combined.
Add the vanilla, and then the baileys a little at a time beating fully in-between each go!
Decoration
Pipe the frosting onto the top of the loaf cake, and then decorate how you want with sprinkles and truffles
Notes
Make sure to only fill your tin 2/3 full as loaf tins vary drastically in size
Use block butter for the frosting so it stays thick
This cake lasts for 3-4+ days at room temp, or freezes well for 3+ months.