Boil pasta for 8 minutes if making mac and cheese right away, or 7 minutes if making it the night before to prevent overcooking as it absorbs cheese sauce.
Always shred your own cheese; pre-shredded cheese contains starches that can make mac and cheese grainy.
When adding seasonings to melted butter, cook for 30 seconds to "bloom" them and enhance flavor.
Cook the roux (butter and flour mixture) for 2-3 minutes to avoid a grainy mac and cheese.
Add evaporated milk gradually to the roux, whisking constantly to prevent lumps.
When adding cheese to the béchamel, ensure the heat is on low to prevent the cheese from curdling.
Add cheese in batches, allowing each batch to melt completely before adding more.
If you don't like Dijon mustard, you can omit it from the recipe.