Butterfly each of the chicken breasts, making a total of 4 thin chicken breasts. Then flatten with a mallet so that they are uniform in thickness, about 1/4".
Put the pretzels in a food processor and grind until fine. Put the crumbs in a shallow dish. Combine with paprika and season with salt and pepper. In another shallow dish, beat the eggs with a splash of water.
Preheat a large non-stick skillet with a 1/4-inch of vegetable oil over medium-high heat.
One at a time, coat each chicken breast in the egg and then the ground pretzels.
Add the pretzel-coated chicken breasts to the hot oil. Cook in a single layer, in 2 batches if necessary, about 3 or 4 minutes on each side, until cooked through.
Meanwhile, make the sauce. In a saucepan, melt the butter. Whisk in the flour and cook for 1 minute. Whisk in the milk and cook until slightly thickened, 3-5 minutes. Stir in the cheese, mustard, paprika and cayenne. Season with salt and pepper.
Serve chicken breasts with a drizzle of cheddar-mustard sauce and a sprinkle of parsley and red onion.
Video
Notes
How to Make Ahead & Store
Store any leftovers in an airtight container in the refrigerator. Reheat the chicken in a 350-degree oven for about 20 minutes, or heat it in your air fryer (this keeps it crispy). Store the cheese sauce separately, and reheat in the microwave or in a small saucepan over low heat.
Variations
Cheese Sauce: Use pepper jack cheese for a nacho cheese sauce vibe. Or you could even use Swiss cheese instead of the sharp cheddar and season it with some thyme and black pepper. Don’t love cheese? Swap in thishoney mustard sauceinstead.
Breading: Swap the pretzels for tortilla chips to make thistortilla chip crusted chicken. Or, you can use panko or seasoned breadcrumbs.
Chicken Tenders: You can use chicken tenders instead of chicken breasts and dip your tenders into the cheese sauce.