Preheat oven to 450ºF.

Melt butter in a large skillet or Dutch oven over medium heat; add flour and cook, whisking constantly, until a blonde roux is achieved, about 3 minutes. Add salt, pepper, and Creole seasoning; whisk. Slowly add half & half and evaporated milk, whisking constantly; add Velvetta cheese and whisk until melted and smooth. Cook sauce until it is thick enough to coat the back of a spoon, about 15 minutes. Remove from heat. Add cooked macaroni; blend. Pour mixture into a greased 9x13 baking dish. Scatter shredded Cheddar evenly atop. Bake until bubbly and golden, about 10 minutes.