Boil water in a large pot.
Add salt to the water.
Put pasta in boiling water.
Cook for 8-10 minutes until tender.
Drain and set aside.
Heat olive oil in a pan.
Add sliced mushrooms to the pan.
Cook for 5 minutes until golden brown.
Mushrooms should be soft and fragrant.
Add minced garlic to the mushrooms.
Cook for 30 seconds until fragrant.
Add spinach leaves to the pan.
Stir until spinach wilts completely.
Pour heavy cream into the pan.
Stir everything together gently.
Let it simmer for 3 minutes.
Add parmesan cheese and stir well.
The sauce will become thick and creamy.
Add cooked pasta to the sauce.
Toss everything together until pasta is coated.
Season with salt and black pepper.
Add red pepper flakes if you like.
Serve hot and enjoy immediately.