Bring a large pot of salted water to a rolling boil over high heat. Add the spaghetti and cook according to package instructions until al dente, about 8-10 minutes. Reserve ½ cup of pasta water, drain spaghetti, and set aside.

In a large skillet, heat over medium heat and add the thick-cut bacon. Cook for 5-7 minutes until crispy and golden brown, remove from skillet, and drain on paper towel, leaving some bacon fat.

In the same skillet with the bacon fat, add the sliced mushrooms over medium-high heat. Sauté for about 5-7 minutes until browned and tender.

Mix minced garlic into sautéed mushrooms and cook for another minute until fragrant, stirring frequently.

Reduce heat to medium, add canned pumpkin puree, dried thyme, smoked paprika, nutmeg, salt, and pepper. Stir together and heat through for 2-3 minutes.

Slowly pour in heavy cream while mixing continuously, then add grated Parmesan cheese. Stir until the cheese has melted and sauce thickens, about 2-3 minutes.

Add cooked spaghetti to the sauce, tossing gently to coat. If the sauce is too thick, gradually stir in reserved pasta water until desired consistency is reached.

Plate the spaghetti, topping each serving with crumbled bacon and freshly chopped parsley. Offer additional grated Parmesan cheese if desired.