1. Cook the pasta according to the package instructions, reserving about 1/4 cup or 60ml of the cooking water.

2. Drain the pasta and set it aside.

3. In a pan, cook the chopped bacon over medium heat at 325°F or 165°C until crispy.

4. Remove the bacon from heat and set it aside on a paper towel to drain excess fat.

5. In the same pan, add the sliced yellow onion and cook until softened, without browning.

6. Add the sliced mushrooms and continue cooking until they are tender and the liquid has evaporated.

7. Add the cooked bacon back into the pan.

8. In a separate saucepan, combine the heavy cream and cheddar cheese.

9. Heat the mixture over low heat at 275°F or 135°C, whisking continuously, until the cheese is melted and the sauce is smooth.

10. Season the sauce with salt and pepper to taste.

11. Add the cooked pasta to the cheese sauce and toss until well combined, adding some of the reserved pasta water if needed.

12. Finally, add the bacon and mushroom mixture to the pasta and toss everything together.

13. Serve hot, garnished with chopped parsley if desired.