Preheat the oven to 375 degrees.
Heat the olive oil in a pan over medium high heat. Season the chicken breasts on both sides with salt and pepper.
Place the chicken in the pan and sear on both sides until golden brown.
In a small bowl, whisk together the grainy mustard, Dijon mustard, honey and butter.
Coat a rectangular baking dish with cooking spray.
Spread half of the sauce into the bottom of the dish.
Arrange the chicken breasts on top of the sauce, then drizzle the remaining sauce over the top of the chicken.
Cover with foil, then bake for 20 minutes. Uncover and bake for an additional 10 minutes or until chicken is cooked through.
Sprinkle with parsley, then serve.