Begin by bringing a large pot of salted water to a rolling boil. Carefully add the jumbo pasta shells and cook them according to the package instructions until they reach al dente, typically around 10-12 minutes. Once done, drain the shells and gently rinse them under cold water to stop the cooking process. Set them aside on a clean kitchen towel.

In a mixing bowl, combine the canned pumpkin puree, ricotta cheese, and smoked Gouda, reserving some Gouda for topping. Season the mixture generously with salt, pepper, and finely chopped fresh sage. Stir well until the ingredients are evenly blended.

Take each cooked jumbo shell and carefully fill it with the prepared pumpkin filling, making sure not to overstuff. Place the filled shells in a greased baking dish.

In a medium saucepan over medium heat, melt the unsalted butter. After about 4-5 minutes, the butter should turn a beautiful golden brown. Remove from heat and stir in heavy cream, grated Parmesan, and a pinch of salt and pepper until the sauce thickens slightly.

Pour half of the rich brown butter sauce evenly over the stuffed shells. Sprinkle the reserved Gouda over the top.

Preheat your oven to 350°F (175°C). Once heated, place the baking dish in the oven and bake the assembled stuffed shells uncovered for 25-30 minutes.