Cook the Bacon: Heat a large skillet over medium heat. Cook chopped bacon until crispy, about 7-9 minutes. Remove bacon and drain on paper towels, leaving 1 tbsp of bacon fat in the skillet.

Sauté the Onion and Garlic: Add diced onion to the skillet and cook until translucent, about 3-4 minutes. Stir in minced garlic and cook for 30 seconds until fragrant, avoiding browning the garlic.

Boil the Spaghetti: Cook spaghetti in salted boiling water according to package instructions. Reserve ½ cup pasta water before draining.

Make the Cream Sauce: Lower the heat and add heavy cream, Parmesan, black pepper, salt, and Italian seasoning to the skillet. Simmer for 2-3 minutes, stirring often, until the sauce thickens slightly.

Toss in the Pasta: Add cooked spaghetti to the skillet and toss to coat with the sauce. If the sauce is too thick, add reserved pasta water a little at a time to adjust the consistency.

Mix in the Bacon: Stir in crispy bacon pieces until evenly distributed.

Optional Cream Boost: Remove the skillet from heat and quickly stir in the egg yolk for extra creaminess.

Garnish and Serve: Sprinkle fresh parsley on top and serve hot.