Recettes swamp water

Freshly ground black pepper, 1 teaspoon salt, or to taste, 1 Tablespoon grated onion, 3 Tablespoons (1 1/2 oz/45 g) butter, 1 1/2 lb (750 g) pumpkin, seeded and cut into large cubes, 3 cups (24 floz/750 ml) milk, 1/4 cup (2 oz/60 ml) cooked white rice