- Preheat oven to 375°F and grease a 9x13-inch baking dish. 
- Cook bacon in skillet until crispy, then crumble and set aside. 
- In same skillet, cook chicken in bacon drippings with half the ranch mix until golden. 
- Boil pasta until al dente; drain well. 
- Whisk sour cream, mayonnaise, milk, remaining ranch mix, garlic powder, and pepper. 
- In a large bowl, combine pasta, chicken, and most of the bacon. 
- Add ranch sauce and 1.5 cups cheddar; mix until coated. 
- Transfer to baking dish, top with remaining cheese and bacon. 
- Cover with foil and bake 25 minutes, then uncover and bake 15–20 more until bubbly and golden. 
- Rest 5 minutes before serving; garnish with parsley.