1

Make a roux.

2

Melt butter over medium heat.

3

Whisk in flour.

4

Cook, stirring frequently, until roux starts to look drier, about 5 minutes.

5

Don't let roux get too dark.

6

Add cold milk in a steady stream, whisking constantly.

7

Bring bechamel to a boil, whisking often.

8

Add cayenne, mustard, and salt to taste.

9

Let boil for a minute or two, until sauce thickens.

10

While bechamel is cooking, fry bacon, and drain on paper towels.

11

Chop roughly.

12

Cook macaroni according to package directions and drain.

13

Grate cheese.

14

Reserve 4 cups to top casseroles.

15

Stir the rest into the finished sauce, along with the parmesan.

16

Stir until relatively smooth.

17

Add macoroni and combine.

18

Pour mixture into three greased shallow hotel pans.

19

Sprinkle reserved cheddar and bacon on top.

20

Bake in preheated 350F oven for 20 to 30 minutes, until bubbly.