Mix the soft butter or margarine as well as the oil and sugar well. Then mix the oat flakes with the chopped almond flakes. Add the flour sifted with baking powder and salt and the lemon zest.
Shape the dough into approx. 12-14 small cakes and place them on a baking tray lined with baking paper. Bake at 160 ° C (fan oven) for about 20 minutes until the cakes are golden brown and sprinkle with powdered sugar before serving.