From my ex-mother-in-law. Best stuff I've ever had (no surprise, she's from Wisconsin.)

Ingredients:
3 tbsp butter
1 onion (chopped)
4 tbsp flour
2 cups milk
7-8 oz. cooked elbow noodles
8 oz. Kraft American cheese (cubed)
6-8 oz. sharp cheddar cheese (shredded)
1 tbsp dry mustard
1 dash cayenne pepper
1 dash salt
1 dash nutmeg

Hardware:
Buttered casserole dish
Large saucepan

Prep:
1. Separate out 4 oz. of sharp cheddar cheese
2. Separately cook the elbow macaroni however indicated on its packaging
3. Pre-heat oven to 375�

Instructions:
1. In the saucepan, saut� the butter and onion until the the onion is translucent
2. Add flour, cook until it is fully incorporated, then take off the stove
3. Add the milk, put back on the stove and bring to a simmer
4. Add dry mustard, cayenne pepper, and salt
5. Add (slowly and until melted) the Kraft American cheese and 4 oz. of sharp cheddar cheese
6. Add the cooked elbow macaroni
7. Mix very, very well then pour the mixture into the casserole dish
8. Sprinkle the remaining 2-4 oz. of cheddar cheese over the top
9. Bake in 375� oven for 30 minutes