If pairing with pulled pork, wait until pork is done to start. Cook pasta according to packaging. Strain and set aside.
Heat a large cast iron skillet on medium heat. We made over the campfire but can do on stove or grill.
To the skillet add the butter until it melts. Whisk flour into the melted butter. Slowly pour in milk and evaporated milk and continue stirring. Add in the salt, onion powder, garlic powder, and ground mustard. Stir. Toss in the 5 cups cheddar while stirring constantly until melted and bubbly. Once sauce is bubbly and starting to thicken (approximately 5 minutes), throw in cooked pasta and mix again.
Add remainder of cheese to top. Cover with foil sprayed with non-stick cooking spray for a few minutes until cheese melts. Optional: If doing over a campfire, add a flaming log/coal from the fire to the top of the foil to help melt/char the cheese. May also broil in the oven if desired.
Add pulled pork, drizzle with barbecue sauce, and top with jalapeños.