Preheat oven to 375 degrees. Spray a 9x9 baking dish with nonstick spray.
Cook your bacon until brown and crispy. (This is the easiest way to cook baconin the oven!) Reserve 1 tablespoon fat and drain the remaining excess fat. Transfer to a paper towel-lined plate and set aside.
Cook your pasta according to the package directions in a large pot of boiled salted water. Drain well.
While the pasta is cooking, make your homemade alfredo sauce. Melt the butter in a saucepan over medium heat. Add garlic (fresh or jarred) and cook for about 1-2 minutes, stirring frequently.
Gradually whisk in heavy cream. Cook for about 1-2 minutes while continuing to whisk constantly. Stir in Parmesan cheese and cook for an additional 2 minutes. Add salt and pepper to taste.
Chop chicken into bite sized pieces.
In a large Ziploc Bag (gallon size), add chopped chicken, 1tbsp olive oil and ranch dressing seasoning. Shake chicken to coat thoroughly.
Add chicken to the 1 tbsp bacon fat and cook for about 2-3minutes just to warm the chicken up.
Add pasta to the baking dish and top with chicken and alfredo sauce. Top with cheeses and bacon.
Cook in oven and bake for 15-20 minutes and the casserole is bubbly and heated through. Serve immediately.