Preheat oven to 350 degrees. Butter bottoms and sides of a 9x13 or similar sized baking dish.
Cook macaroni noodles according to package directions. Drain and set aside.
In a medium sized sauce pan over medium heat, melt butter. Whisk in flour. Next whisk in milk. Cook until mixture thickens (close to the consistency of glue), about 5 minutes.
Place eggs in a small bowl and whisk well. Then, very slowly whisk about ½ cup of the butter & milk mixture into the eggs. Once well mixed, slowly pour the mixture back into the pot while continuously whisking. Stir in shredded cheddar, pepper, seasoned salt, and salt.
In a large bowl, stir together noodles and cheese mixture. Pour into prepared baking dish.
Cover top of dish with the cheddar slices.
Bake for 20-25 minutes, or until cheese is bubbly.