Boil a large pot of water just 24 hours before you serve the gratin. Pour 2 tbsp of salt in it along with the macaroni. Keep cooking it for four minutes; keep it aside after draining.

Take a medium-sized bowl and pour nutmeg, cream, 1 cup of the Gruyere, 2 tsp salt, ½ cup of the Cheddar, 1 tsp pepper, and blend together. Stir the pasta into the cream mixture when it is nicely done, use plastic wrap to cover up the bowl and keep it in the refrigerator for the whole twenty-four hours. The whole cream will be absorbed by the pasta.

Allow the mixture to settle at room temperature for 1 hour when you are ready to cook. Get the oven ready by preheating it to 400 degrees.

Take a 2-quart gratin dish and butter it, pour the mixture into the buttered dish and roll it out in an even manner. Blend the ½ cups Cheddar with 1 cup Gruyere, and sprinkle it on the top in an even manner. Afterwards, blend 2 tbsp butter and bread crumbs, drizzle it up on top in an even manner. Keep baking it for 20 to 25 minutes, rotate it just a little, bake it to the point it harnesses a lovely golden shade and crusty. Serve the dish while hot.