In a large pot of salted water, cook 16 ounces pasta to desired doneness. Drain and set aside.
In a large pot or Dutch oven, cook 1 pound bacon ends and pieces When done, remove cooked bacon pieces and set aside. Discard bacon grease, reserving no more than a tablespoon in the pot. Add 1 cup sliced fresh jalapeños to remaining bacon grease with bacon. Cook over medium heat until tender and fragrant, about 5 minutes.
Add 4 tablespoons butter to mixture and allow to melt. Reduce heat to low and add 1 cup milk, 2 cups shredded gruyere, and 3 cups shredded sharp cheddar. Stir until melted. As soon as the cheese has melted and a sauce has formed, remove mixture from heat and stir in pasta. Enjoy!