2cupsCheddar cheese, shredded, plus 1 additional cup for topping (3 cups total)
1cupFontina cheese, shredded
1cupWhite Cheddar cheese, shredded
3eggs, beaten
1/2cupsour cream
1cupmilk
1/2teaspoondry mustard
1/2teaspoonsalt
1/2teaspoonblack pepper
Instructions
TO MAKE THE MORNAY SAUCE
In a small saucepan, melt the butter over low heat. Increase the heat to medium and blend in the flour. Cook slowly, stirring, until the butter and flour cook together for 2 minutes (do not allow the roux to brown).
Slowly whisk in the milk and continue to whisk until the sauce thickens and comes to a boil, about 2 to 3 minutes. Reduce heat to a simmer and stir in the cheese. Continue to cook, stirring until thickened, about 5 minutes. Remove from heat. Set aside.
TO MAKE THE MACARONI AND CHEESE
In a large pot of boiling water, cook the macaroni to al dente.
Drain and set aside.
In the slow cooker, combine the butter, 2 cups of the shredded Cheddar, the Fontina, the White Cheddar cheeses, the eggs, and the sour cream together.
Slowly stir in the milk, dry mustard, salt, and pepper.
Add the drained macaroni and stir again.
Top with the additional cup of shredded cheddar cheese.
Set the slow cooker on low setting and cook for 3 hours, stirring occasionally.