Preheat the oven to 400 degrees. Place a stockpot over high heat and when it comes to a boil, add the orzo or shells. Cook until al dente. Drain and set aside. Place the butter in a large skillet over medium heat and cook until browned, about 2 minutes. Add the flour and cook, stirring constantly until it loses its rawness, about 2 minutes. Place the milk in a saucepan and warm it over a medium heat. Add ½ cup milk to the butter mixture and cook, stirring constantly, until it forms a slurry, about 1- 2 minutes. Add the slurry to the milk and cook, stirring constantly, until thickened, about 1- 2 minutes.
Add the powdered cheese to the milk and mix well. Add the orzo or shells and mix to combine. Add the remaining cheese, cream, salt and pepper, mix to combine and transfer to a 2 quart casserole dish. Sprinkle the bread crumbs on top and transfer to the oven. Bake until bubbly and slightly browned, about 7- 10 minutes.