Preheat oven to 350 degrees F. Coat the inside of a 9-inch x 13-inch baking dish with non-stick cooking spray and set aside.
Place a large pot of salted water over high heat and bring to a boil. Cook pasta according to package directions until al dente. (The pasta will cook a little more in the oven.) Drain and transfer to a large mixing bowl.
While the pasta cooks, prepare the ranch sauce. Place a large skillet over medium heat.
Add butter, and once melted add in the garlic. Cook until fragrant, about 30 seconds. Add flour and whisk to combine. Let cook for 1 minute.
Slowly whisk in the milk so you don't get any lumps. Once all the milk is incorporated, add the cream cheese, onion powder, and some salt and pepper to the skillet. Whisk until the cream cheese is melted.
Add ranch dressing, Parmesan cheese, and 1 cup of mozzarella cheese to the sauce. Whisk until cheese is melted. (If the sauce gets too thick, add a little milk until your desired consistency is reached.)
To the cooked pasta, add in the shredded chicken. Pour ranch sauce over the pasta and chicken and stir to coat. Add half of the bacon to the pasta and stir to combine.
Transfer pasta to your prepared baking dish. Spread into an even layer. Top pasta with remaining mozzarella and remaining chopped bacon.
Bake for 25 to 30 minutes until sauce is bubbling and cheese is melted.
Remove from oven and let sit for 5 minutes. Serve warm topped with chopped parsley, if desired.
You can you a store-bought rotisserie chicken or pre-cooked chicken breasts to save time on prep!I make my bacon in the oven while cooking the sauce and pasta.