Line a medium plate with paper towel and set aside.
In a large pan, heat a drizzle of oil over medium-high heat. Add pancetta and toss until crispy for 5-6 min. Transfer the pancetta to the lined plate. Save 1 tbsp fat from the pan and discard the rest.
In the same pan over medium heat, cook onion, garlic, thyme and mushrooms for 7-8 min, stirring occasionally.
Add in the pasta, pasta water, sour cream, half the lemon zest, and 1 tbsp lemon juice, then toss together with mushrooms & spinach for 1 min. Season with salt and pepper, and add 1 tsp lemon juice at a time to taste.
Plate pasta and top with crispy pancetta and remaining lemon zest. Enjoy!