Coffee Hazelnut Friands

Lovely tiny rich nutty cakes. Friands tends to be quite sweet, and when made with coffee in it, the sweetness will be greatly offset, and it’s just nice for me.
Keep them (airtight) overnight and they turn so tender and fragrant.

185g salted butter
1 Tbsp instant coffee
180ml egg white ( from 5 Grade A eggs , 63-65g shells on)
100g ground hazelnuts
100g soft brown sugar
75g plain flour
100g icing sugar
1/4 tsp vanilla extract
More butter for greasing the pan