Start by bringing a large pot of salted water to a rolling boil. Once boiling, add spaghetti and cook for 8-10 minutes until al dente, reserving half a cup of pasta water before draining.

In a medium bowl, whisk together egg yolks, one whole egg, and Parmesan cheese until smooth and creamy. Set aside.

In a frying pan, heat and cook diced bacon for 5-7 minutes until crispy. If using, add garlic in the last minute. Remove bacon and set aside, leaving the fat in the pan.

In the same pan, add sliced mushrooms and cook for 4-5 minutes until golden and tender. Stir occasionally.

Reduce heat to low, add drained spaghetti, and toss with crispy bacon. Add half of the reserved pasta water.

Quickly pour the egg and cheese mixture over the hot spaghetti and toss to coat. Add more pasta water as needed for creaminess.

Season the carbonara with salt and pepper to taste. Serve hot, garnished with additional cheese and pepper.