I used my bogstandard shortbread recipe but replaced the caster sugar with brown, half of the butter with hazelnut oil and a third of the flour with ground hazelnuts.
So
1 quantity of fine brown sugar eg 50g
2 of butter or oil and butter eg 100g
3 of flour or flour and ground nuts (keep the semolina* if you like) eg 150g
Mix the fat and the flour, then add the sugar, press into a pan, bake at 160 for about 20 to 30 minutes, keep looking. I rolled the mixture into marbles and pressed them down a bit with a fork.
*I weigh out my flour then remove a couple of tablespoons of it and replace with a couple of tablespoons of fine semolina for that slight bite.