Preheat oven to 425°. Boil water and salt liberally. Cook 1 lb macaroni noodles in a Dutch oven or stainless steel pot til al dente

In a sauce pan on medium low heat, melt 4 tbsp butter. Add 5 tbsp flour and whisk until incorporated. Cook roux until it changes color slightly, just a bit darker. Add pickling juice from jarred sliced jalapeños and whisk again.

Add ground mustard, nutmeg, salt, pepper, sour cream and milk to roux, whisk til smooth. Cook on medium heat, stirring occasionally, until mixture begins to bubble slightly and is thick, nearly the consistency you want the cheese sauce to be, slightly thinner than.

Add cheddar and havarti cheeses. Hand grating these cheese from a block is preferable to using bagged cheese, as bagged cheese contains cellulose, to prevent caking, which dried your sauce. If you use bagged cheese, increase milk by 1/4 cup. Stir sauce until cheese is fully melted and incorporated. Keep on very low heat and stir frequently, if you need to keep the sauce warm. Cheese will burn to the bottom easily!

In a small bowl, melt a pat of butter. Toss bread crumbs, butter, and parmesan cheese together.

Mix cheese sauce into cooked, drained macaroni. If your cooking vessel isn't oven safe, pour your macaroni and cheese into a large greased baking dish. Spread diced jalapeños over mac and cheese, then top with bread crumbs. Bake at 425° for 5-7 minutes, until bread crumbs are golden brown and sauce bubbles in some spots in between. Serve and enjoy!