Mix the butter with a hand mixer until creamy. Stir in sugar and flavorings until a combined mixture is formed. Beat in the eggs one at a time for about 30 seconds. Mix the oat flakes with ground almonds and baking powder and stir in two thirds of it. Fold in the rest with your hands on a lightly floured dough surface. Form the dough into rolls, about 3 cm in diameter, wrap in cling film and put in the fridge for a few hours. Cut the dough rolls into slices approx. ½ cm thick and place them on a baking tray lined with baking paper. Bake in a preheated oven at 160°C for about 12 minutes. Let cool and enjoy.