Cook pasta according to package directions until al dente, 8 to 10 minutes, then drain. Meanwhile, slice pancetta into long, thin strips. If using bacon, thinly slice. Set a large frying pan, preferably non-stick, over medium heat. Add pancetta. Stir often until it begins to crisp, 2 to 3 minutes. Bacon will take about 6 minutes. Add onion and mushrooms. Pan will be very full. Stir often until onion begins to soften and mushrooms begin to brown, about 6 minutes. Remove to a large bowl.
Pour cream into frying pan. Increase heat to medium-high. Stir frequently until boiling, 1 to 2 minutes. Reduce heat to low. Gradually stir in cheese, then butter, and stir constantly until melted. Remove from heat. Then add spinach and drained pasta to pancetta mixture in large bowl. Pour cream sauce overtop and stir until evenly mixed. Serve immediately, sprinkled with a little more Parmesan, if you wish.
Nutrition (per serving)
Pamper your mom this year by making her a decadent, fresh spring pasta.