For the coconut cake, beat the butter until soft. Stir in lemon zest, salt, sugar. Fold in eggs one at a time. Mix almond kernels and baking powder, add and fold in coconut flakes.
Line a 24 cm cake springform pan with baking paper, grease and flour the edges. Pour in the mixture and bake in a heated oven at 180 degrees on the lowest rack for about 55 minutes.
If desired, spread with warmed apricot jam and sprinkle with toasted coconut flakes.