Great Grammy's Macaroni & Cheese

This has been requested frequently enough that I will finally submit it. This is known as Great Grammy's mac & cheese thanks to my children. It's my grandmother's recipe. I spent a day watching very carefully & making notes. ;) I don't always bake it. Sometimes I just pour the cheese sauce over the macaroni & start eating! The dish I bake this in is a Corningware Cornflower 3 quart dish - it is square with high sides vs. rectangular like a smaller 9x13x2.

• Ready In: 1 hr 30 mins
• Serves: 8

Ingredients

• 1  lb elbow macaroni
• 2  tablespoons butter
• 3  tablespoons all-purpose flour
• 1⁄2 teaspoon ground mustard
• 1  pinch salt
• 1 1⁄2 cups  whole milk, warmed
• 1⁄2-3⁄4 lb cheddar cheese, extra sharp, white, cubed
• 4  slices American cheese, white
• 1⁄2 cup parmesan cheese, grated, maybe more
•  ground black pepper

Directions

1. Preheat oven to 350°F Grease casserole dish. Cook macaroni in boiling, well salted water until al dente. Drain.
2. Melt butter in top of double boiler. Add salt, ground mustard & flour, whick until smooth. Whisk in milk until smooth. Heat until thickened. *I will take the top of the double boiler & put it on direct heat BUT keep it low & do not stop stirring or it will burn & be ruined!*.
3. Add cheese & whisk until melted.
4. Put 1/2 cooked macaroni in casserole. Pour about 1/3 cheese sauce over macaroni. Stir well. Lay slices of American cheese over this. (4 slices fit my dish perfectly.) Add rest of macaroni & sauce. Stir carefully. Sprinkle top with Parmesan cheese to cover & some pepper to taste.
5. Bake 1 hour until top is browned & bubbly.