Take the puff pastry out of the refrigerator 5-10 minutes before use. Cut out 6 circles (approx. cm 12 Ø) from the dough. Prick the dough with a fork and place it on a baking tray lined with baking paper.
Wash the rosemary, shake dry and remove the needles. Peel potatoes and cut them into slices (2-3 mm thick). Heat 20 g butter in a pan. Lightly fry the potato slices for 10-15 minutes.
Add half of the rosemary about 2 minutes before the end of the cooking time. Season potatoes with salt and pepper. Finely chop the remaining rosemary needles.
Onions peel and chop finely. Heat 20 g butter in a pan. Sauté the diced onions for 10-15 minutes over medium heat. Season with salt and pepper and add chopped rosemary.
Add the liqueur and simmer for about 10 minutes until the liquid has evaporated.
Peel the skin off the veal sausage. Heat the oil in a pan. Fry the veal sausages for about 3 minutes, turning them over. Cut sausages into 2-3 mm thin slices. Spread puff pastry with onion confit, spread Weißwurst and potato slices fan-shaped.
Bake the Tartelettes in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 15-20 minutes until the dough is golden brown. Serve immediately.