1. Cook the diced pumpkin (pumpkin and potatoes) in a Dutch oven with butter and a little water for about 15 minutes.
2. The flesh should become mashed. If there is any remaining juice, evaporate it by removing the lid and increasing the heat.
3. Season with salt and pepper, and add grated nutmeg.
4. Peel and chop the onions and garlic cloves, and cut the smoked bacon into very small lardons.
5. Rinse the parsley, drain it, and finely chop it.
6. Heat 40 g of butter in a frying pan and melt the chopped onions and garlic without browning them.
7. Then add the ground beef and bacon, mix, and cook for 2 minutes over medium heat. Add the chopped parsley, salt, and pepper.
8. Preheat the oven to 210°C (thermostat 7).
9. Pour the meat mixture into the bottom of a gratin dish (no need to butter it), cover with a layer of pumpkin (/potato) mash. Smooth the surface, sprinkle with Parmesan, and distribute the remaining butter in small pieces.
10. Bake for about 20 minutes to gratin. Serve very hot in the baking dish.
11. The bacon can be replaced with a sausage cut into small pieces.