1 (16-ounce) box uncooked macaroni noodles
1 1/2 teaspoons salt, divided
2 cups sharp cheese, shredded
2 cups mild cheese, shredded
1/2 cup (1 stick) butter
8 eggs
1 1/2 cups milk

Boil noodles according to directions on package, adding at least 1 teaspoon of salt to water. Drain noodles and let cool.
Preheat oven to 350 degrees. Coat a 9- by 13-inch casserole dish with non-stick cooking spray. Layer half of macaroni in baking dish. Cover with 1 cup of the sharp and 1 cup of the mild cheese. Repeat. Melt butter in microwave and pour over cheese. In a separate bowl whisk together eggs, milk and 1/2 teaspoon of salt. Pour over macaroni. Bake at 350 degrees for 30 minutes.