Cut the pumpkin in half and remove the seeds.
Place the pumpkin in a steamer and steam for 15 minutes.
Finely chop the onion and bacon.
Melt butter in a pan, then sauté the onion and bacon.
Add milk and salt, and bring to a gentle simmer.
Scoop out the cooked pumpkin flesh and place it in a bowl.
Mix the sautéed ingredients, pumpkin flesh, and cheese together.
Stuff the mixture back into the pumpkin shells.
Top with mozzarella cheese and bake in the oven at 180°C for 10 minutes.