In a 9” X 13” baking dish, combine the butter with the maple syrup, mustard, curry powder and cayenne. Bake for about 5 minutes, until the butter is melted. Whisk in a generous pinch each of salt and pepper and let cool slightly, 5 to 10 minutes.
Reset oven temperature to 425º F.
Season the chicken with salt and pepper, add to the baking dish and turn to coat with the sauce. Bake for about 15 - 18 minutes, basting halfway through, until an instant-read thermometer inserted in the thickest part registers 165º F. (Cook time depends on the thickness of the chicken breasts.)
Allow chicken to rest for 5 minutes. Place on serving plates.