Preheat oven to 400 degrees. Line bottom and sides of a 9x9 baking pan with tin foil. Generously brush the foiled pan with 1 Tbsp. of the melted butter. Mix remaining melted butter with bread crumbs, Four Cheese, and pepper until it reaches the texture of wet sand. Sprinkle half of the bread crumb mixture into the prepared pan.
Bring a medium pot of salted water to boil. Add macaroni and follow package directions to cook until al dente. Drain macaroni and set aside. Place heavy cream, cream cheese, eggs, mustard, and creole seasoning in a large mixing bowl. Beat mixture on low speed with an electric mixer (or whisk by hand) until combined. The mixture might have small lumps, that’s okay. Add cooked macaroni, cheddar, and Monterey Jack, and stir until combined. Place macaroni mixture into the pan evenly. Sprinkle the top of the macaroni with remaining bread crumb mixture.
Bake 25 to 30 min. or until bread crumbs are golden brown. Let cool for 20 min. Remove macaroni mixture out of pan by lifting out the tin foil. Slide macaroni off of the foil onto a cutting board. Using a bread knife to cut macaroni into squares or rectangles. Cool for 5 more min. before serving.