Boil pasta in salted water according to package directions until al dente. Reserve ½ cup pasta water before draining. The starchy water helps sauce cling to noodles perfectly.
Cook turkey bacon in a large skillet over medium heat for 6-8 minutes until crispy and browned. Transfer to paper towels to drain. Once cooled, crumble into bite-sized pieces for topping.
Drain excess grease leaving about 1 tablespoon in the pan for flavor. Add olive oil if needed to coat the bottom. This flavorful fat base makes mushrooms taste incredible.
Sauté mushrooms in the same skillet for 5-7 minutes without stirring too much. Let them brown properly for deep, caramelized flavor. Crowding or constant stirring steams them instead of browning.
Add garlic and cook for 1 minute until fragrant but not burned. Garlic burns quickly, so watch carefully. The aroma should fill your kitchen when it's ready.
Stir in pumpkin puree along with thyme, smoked paprika, nutmeg, salt, and pepper. Cook for 2-3 minutes, stirring constantly so flavors meld together. The sauce should darken slightly and smell amazing.
Pour in cream and Parmesan while stirring to combine everything into a smooth, velvety sauce. Simmer for 2-3 minutes until cheese melts completely and sauce thickens slightly.
Add cooked spaghetti to the sauce and toss with tongs to coat every strand evenly. Add reserved pasta water 2 tablespoons at a time if sauce seems too thick. The pasta should be completely coated and glossy.
Season to taste with additional salt and pepper if needed. The sauce should be well-seasoned and flavorful. Taste before serving and adjust as needed.
Serve immediately topped with crumbled turkey bacon, fresh parsley, and extra Parmesan. The contrast between creamy pasta and crispy bacon makes every bite perfect.