Bring a large pot of salted water to boil. Cook macaroni one minute less according to package directions. Drain completely and set aside.
In a large pot, melt butter over medium heat. Whisk in flour and cook 30 seconds. Pour in milk and continue whisking until sauce thickens. Add in salt, nutmeg and cream cheese cubes. Whisk until completely melted. Slowly add in remaining cheese and whisk until thick and creamy. Remove from heat. Stir in macaroni to coat in sauce.
Pour into a baking dish and sprinkle with breadcrumbs. Bake 10-15 minutes and serve.