Spray 13x9-inch (3-quart) glass baking dish with cooking spray, set aside.
In 5-quart Dutch oven, melt 2 tablespoons of the butter over medium heat, Stir in onion, salt and pepper; cook, stirring occasionally, about 5 minutes or until softened and golden brown.
Stir in broth and cream; heat just to boiling over medium heat, stirring frequently. Remove from heat; fold in potatoes. Stir in Parmesan cheese. Spread in baking dish. Cover with foil; refrigerate up to 24 hours.
Heat oven to 350°F. Bake uncovered 30 minutes.
Meanwhile, in small microwavable bowl, microwave remaining 1/4 cup butter uncovered on High 15 to 20 seconds or until melted. Stir bread crumbs into melted butter; set aside.
Remove potatoes from oven; sprinkle bread crumbs on top. Return to oven; bake 40 to 50 minutes longer or until topping is golden brown and edges are bubbly. Let stand 5 minutes before serving.