- 20 minutes
- 1 hour
- Place the chicken breasts in a buttered baking dish (use approximately 1 tablespoon of the butter for this). Salt and pepper the chicken.
- Bake the chicken in a 375-degree oven for about 20 to 25 minutes.
- In a medium saucepan, heat the remaining 3 tablespoons of butter and add the onions. Cook for several minutes until they begin to soften, stirring regularly. Stir in the garlic powder.
- Slowly stir in the flour and cook for a few more minutes, until it's the consistency of a brown paste.
- Add the milk, whisking continually on medium heat. The sauce will begin to thicken.
- Add the mustard, the cheddar, and half of the parmesan and stir continually until the cheese is melted.
- When the chicken is finished cooking, remove it from the oven and pour the cheese sauce on top of the chicken. Sprinkle the panko breadcrumbs and the remaining Parmesan cheese on top.
- Return to the oven and bake for another 20 to 30 minutes or until the chicken is thoroughly cooked and reaches an internal temperature of 165 degrees Fahrenheit as indicated by a meat thermometer.
- Top with fresh parsley.