Bring a large pot of salted water to a boil. Cook pasta until al dente, and reserve 1 cup of pasta water before draining.
12 ounces dry spaghetti
In a mixing bowl, whisk together the eggs, Parmesan, and 1 teaspoon black pepper. Set aside.
2 large eggs, 1 cup freshly grated Parmesan, 1 ½ teaspoons freshly cracked black pepper, 2 egg yolks
Heat olive oil in a large skillet over medium heat. Add bacon and cook, stirring often, until bacon is crispy. Add garlic and cook for an additional minute, or until fragrant.
2 Tablespoons olive oil, 5 bacon strips, thick-cut, 3 cloves garlic
Transfer bacon and garlic to a medium bowl, leaving 2 tablespoons of bacon grease in the pan.
Season chicken with remaining ½ teaspoon black pepper and ½ teaspoon salt. Set the skillet over medium heat and add chicken. Cook until golden brown and cooked through; 6 to 8 minutes.
½ teaspoon Kosher salt, 1 pound boneless skinless chicken breast
Transfer chicken to the bowl with bacon and garlic.
Reduce heat to medium. Add reserved pasta water, along with the spaghetti. Toss together until the sauce starts to thicken.
Reduce heat to low. Pour egg mixture into the skillet and toss pasta until sauce is thick and the eggs are cooked, but not scrambled or curdled; about 4 minutes. Add the bacon and chicken back to the skillet and stir to combine.
Taste and adjust for salt and pepper. Serve warm, garnished with freshly grated parmesan and parsley, if desired.
fresh chopped parsley