First, cook the pasta in salted water until done. Drain and keep aside. Reserve ½ cup of pasta water for later use.
While the pasta is cooking, to a hot pan add chopped bacon. Cook until bacon is crisp and brown in colour.
Remove cooked bacon from the pan. Reserve 2 tablespoons of bacon fat in the pan and discard the rest.
Add olive oil to the same pan.
Add mushroom to the pan and arrange sliced mushrooms in a single layer(Don't overcrowd the pan).
Cook mushroom undisturbed until they are golden brown in colour on one side. Then flip and cook the other side.
When Mushroom is cooked on both sides and it is crispy golden brown. It should take roughly 8-10 minutes.
Add minced garlic, oregano and chilli flakes. Stir on low heat till aromatic.
Add ½ cup of reserved pasta water and cook for a minute. The water will start to thicken and form a sauce.
Add Cooked spaghetti and cooked bacon to the pan. Add salt as per taste (remeber there is salt in pasta water).
Toss everything well and cook until the pasta water has reduced and almost thickened.
Serve with fresh parmesan cheese on top.