Cook the chopped bacon in a large Dutch oven or deep skillet over medium heat for 6–8 minutes, stirring occasionally, until crisp. Transfer the bacon to a paper-towel-lined plate and leave about 1 tablespoon of bacon fat in the pot.

Add the chicken pieces to the bacon fat and cook for 3–5 minutes, stirring, until lightly browned. The chicken does not need to be fully cooked at this stage because it will continue cooking with the pasta.

Add the chopped onion and cook for 2–3 minutes until it begins to soften. Stir in the minced garlic and cook for about 30 seconds, just until fragrant.

Add the ranch seasoning, low-sodium chicken broth, heavy cream, and uncooked pasta. Stir well while scraping the browned bits from the bottom of the pot into the sauce.

Bring the mixture to a gentle boil, then reduce the heat to medium-low. Cover the pot partially and simmer for 12–16 minutes, stirring every few minutes, until the pasta is tender and most of the liquid has been absorbed.

Remove the pot from the heat before adding the cheddar and mozzarella. Stir until both cheeses melt into a smooth, creamy sauce.

Fold most of the cooked bacon into the pasta and taste the sauce. Adjust the black pepper or ranch seasoning if needed, then garnish with the remaining bacon and chopped parsley or green onions.