1. Bring a large pot of salted water to a boil. Cook the jumbo pasta shells until al dente, drain, and set aside to cool slightly.

2. In a bowl, mix together the pumpkin puree, gouda, ricotta, 1/4 cup of Parmesan, egg, salt, pepper, and nutmeg until smooth.

3. In a large skillet, melt butter over medium heat. Add sage leaves and cook until butter browns and smells nutty. Add garlic and cook 30 seconds. Pour in heavy cream, reduce heat, and simmer until slightly thickened. Stir in remaining Parmesan, salt, and pepper.

4. Preheat oven to 375°F. Fill each shell with the pumpkin-gouda mixture and arrange in a greased baking dish. Pour the brown butter Alfredo sauce evenly over the top.

5. Cover with foil and bake for 20 minutes. Remove foil and bake another 10 minutes until golden and bubbly.

6. Serve warm with extra sage or cracked pepper. Store leftovers in an airtight container for up to 3 days.