Preheat oven to 375°F (190°C).
Cook the pasta according to package instructions; drain and set aside.
In a large skillet, heat olive oil over medium heat. Add onion and garlic, sauté until translucent, about 2-3 minutes.
Add the heavy cream and ranch dressing mix to the skillet, stirring well. Bring to a simmer and cook for 5 minutes, until slightly thickened.
In a large mixing bowl, combine the cooked pasta, shredded chicken, crumbled bacon, sauce from the skillet, and half of the shredded cheeses. Season with salt and pepper to taste.
Transfer the mixture to a greased baking dish. Top with the remaining cheeses.
Bake for 20-25 minutes, or until the cheese is bubbly and golden brown.
Garnish with chopped parsley before serving.