1. Clean the mushrooms; gently dry them with a kitchen cloth, and slice them. Chop the parsley. Clean and chop.
2. Cut the bacon into small cubes, and cook them over high heat, in a cast-iron pot, until they are crispy; drain, keeping 3 tablespoons of the cooking fat, then remove the bacon from the pot. Add the mushrooms to the pot, and cook for 3 minutes over high heat, stirring occasionally with a wooden spoon. Add the chopped parsley.
3. Meanwhile, in a large quantity of salted water, cook the bavette pasta al dente.
4. Put 3 tablespoons of the cooking water into a frying pan. Add the softened butter at room temperature; mix well and add the bacon, mushrooms, and egg yolks beaten with the red pepper flakes.
5. Remove from high heat, quickly mix the ingredients and serve immediately from the pan, sprinkled with grated parmesan.