Bring a large pot of water to a rolling boil, then add a generous pinch of salt. Drop in the spaghetti and cook until al dente, typically 8-10 minutes. Reserve ½ cup of the starchy pasta water, then drain the spaghetti and set aside to keep warm.

In a large skillet over medium heat, add thick-cut bacon strips and cook for 5-7 minutes until crispy. Transfer to paper towels to drain excess grease, leaving about a tablespoon of grease in the skillet.

In the same skillet, toss in sliced mushrooms and sauté them in the bacon fat for 5-7 minutes until golden brown and tender.

Stir in the minced garlic and sauté with the mushrooms for about 1 minute until fragrant.

Add the canned pumpkin puree along with dried thyme, smoked paprika, nutmeg, salt, and pepper to the skillet. Stir together and heat for 2-3 minutes.

Pour in the heavy cream and sprinkle in the grated Parmesan cheese. Mix until the cheese melts and the sauce thickens, about 2-3 minutes.

Add the reserved spaghetti to the skillet and toss to coat in the sauce. If too thick, gradually add reserved pasta water.

Serve warm, topped with crispy bacon pieces and fresh parsley.