Start by whisking the eggs and Parmesan in a bowl. This combo is the heart of the creamy sauce. I recommend doing this before anything else to avoid scrambling later.
Dice your bacon and cook it in a skillet over medium heat until crisp. You’ll get delicious brown bits and flavorful grease – don't drain it all! Save a few spoonfuls for cooking the chicken.
Season the chicken with salt and pepper. Add it to the skillet with the reserved bacon grease and cook until browned and cooked through. Then stir in the garlic and cook for another minute. The smell? Incredible.
Boil the spaghetti until al dente. Before draining, scoop out about 1 cup of pasta water. You’ll use this starchy water to help make the sauce creamy and glossy.
Add the cooked pasta to the skillet with chicken and bacon. Remove the skillet from heat to prevent the eggs from cooking too fast. Slowly pour the egg-cheese mixture into the pasta, tossing continuously.
Add reserved pasta water a little at a time until the sauce reaches your desired creaminess. It should coat the noodles without being runny. Garnish with parsley and extra Parmesan, and serve immediately.