Preheat oven to 400 degrees. Line a rimmed baking sheet with foil and spray it with cooking spray.

Trim the chicken and cut it in half lengthwise with poultry shears, so that you have four thinner pieces. Wash and trim the woody ends off the asparagus, then pat it dry.

Combine the olive oil, mustard, garlic, paprika, pepper, and sea salt in a small bowl.

Place the asparagus spears in a large bowl. Add 2 tablespoon of the olive oil & mustard mixture and toss to coat. Arrange the asparagus in a single layer on one end of the prepared baking sheet.

Place the chicken pieces in the same large bowl you used for the asparagus. Add the rest of of the olive oil & mustard mixture, then stir to coat.

Add the chicken to the other half of the prepared baking sheet, then top it with any remaining mustard mixture from the bottom of the bowl.

Bake the chicken & asparagus at 400 degrees for six minutes. Meanwhile, slice the Swiss cheese (if not using pre-sliced).

After six minutes, stir the asparagus and flip the chicken over. Top each piece of chicken with Swiss cheese slices, tearing the pieces to fit.

Roast at 400 degrees for another six minutes, then broil for two minutes to brown the cheese.

Serve the mustard Swiss chicken with its built-in side of asparagus, topped with pan juices.