Cook pasta until almost al dente, then drain, reserving 1/3 cup of pasta water.
Add mushrooms and garlic into a skillet over medium high heat and saute about 6 minutes.
Add the evaporated milk and heat to simmering.
Reduce the heat to medium. Add the spinach in and allow it to wilt.
Add the parmesan cheese and mix well.
Add the pasta and toss to coat.
Cook for another 5-10 minutes to allow the sauce to thicken.