Slice the package of bacon and jalapeño into small strips or bite sized pieces.
Cook the bacon alone in a cast iron skillet until just barely browned, then add the garlic and jalapeño and finish cooking the bacon.
Remove the bacon and pat it dry with paper towel to remove any excess grease.
Drain most of the bacon grease from the pan, leaving around 1-2 Tbsp. Add the butter and once melted stir in flour until a roux is formed.
Slowly mix in milk until the consistency is smooth and creamy, and add the swiss, sharp cheddar, gruyère, and pepper jack cheeses. Stir until all of the cheese is melted.
Mix the cheese sauce into cooked noodles until each piece is evenly coated with cheese
Add the bacon mixture and cover with bread crumbs and extra cheese.
Bake in an oven at 350°F for 30 minutes or until the bread crumbs are brown and crispy.