Well, the recipe says 240ml strong brew of coffee which I assume might be just regular instant, and THEN to add 20g espresso powder to that brew. Yes espresso will probably be potent enough to flavour the cake so I think I'll just make a 2 teaspoon instant coffee brew and then add the espresso. To be honest, I've seen another recipe which simply uses espresso powder mixed with a bit of water and then added to the batter.
Might seem like a trivial detail but with all the ingredients and time taken to make a cake like this, I don't want to ruin it by making it too strong or even too weak. I already threw away two previous coffee cakes and wasted a lot of time snd ingredients! But I won't be beaten (no pun intended)
This was my first cake. Icing tasted very nicely of coffee but not the sponge.