In a large skillet over medium heat, cook the diced bacon until crispy. Transfer cooked bacon to a paper towel-lined plate, reserving ¼ cup for garnish. Drain off excess bacon grease, leaving 2 tablespoons in the skillet.
Add cubed chicken breasts, chopped onion, salt, and pepper to the skillet. Cook until chicken is lightly browned and onions are tender.
Stir in ranch seasoning and chicken stock. Bring to a boil, then add penne pasta. Cover and cook on low heat for 15-20 minutes or until pasta is tender.
Remove lid and stir in cream cheese and cream of chicken soup until smooth.
Add 1½ cups shredded Colby jack cheese, cooked bacon (except reserved ¼ cup), and 1 tablespoon chopped parsley. Stir to combine.
Top with remaining ½ cup shredded Colby jack cheese (do not stir) and cover skillet with lid for 3-4 minutes or until cheese is melted.
Remove lid and garnish with reserved bacon and remaining chopped parsley before serving.