Preheat oven to 400 F degrees. Spray a baking dish with nonstick spray.Bring water to a boil and prepare pasta according to directions, but shaving 1-2 minutes off of the cooking time to keep al dente.Meanwhile, heat butter in medium saucepan over medium heat. When butter begins to sizzle, quickly add flour and whisk constantly until roux is golden, about 2 minutes.
Pour in milk and whisk constantly, stirring until the mixture slightly thickens.Reduce heat to low and add in white cheddar and blue cheese a couple handfuls at a time until cheese melts and sauce is thickened.
Stir in Blue Cheese Dressing. Stir in Instantly Fresh chives and season with salt and pepper.
Add cooked pasta to baking dish. Pour cheese sauce over top, tossing to coat all the noodles.
Cover top in panko bread crumb mixture.Bake for 30-35 minutes, or until top is golden and crunchy and sauce is bubbling. Top with crumbled bacon