01 -
Preheat oven to 190°C (375°F). In a mixing bowl, whisk together coarse mustard, dijon mustard, yellow mustard, honey, and 1 Tbsp olive oil. Spray a 33 cm x 23 cm (13 x 9-inch) baking dish with non-stick cooking spray.
02 -
In a small skillet, heat remaining 1 Tbsp olive oil over medium heat. Add chopped onion and sauté for approximately 8 minutes until golden brown. Add minced garlic and sauté for an additional 30 seconds. Transfer the mixture into the prepared baking dish, spreading it into an even layer.
03 -
Season each chicken breast with salt and freshly ground black pepper on both sides. Arrange chicken on top of the onion layer in the baking dish.
04 -
Pour the mustard mixture evenly over the chicken, ensuring each breast is completely covered. Arrange sprigs of rosemary between the chicken breasts.
05 -
Bake in the preheated oven for 25 to 30 minutes, or until the chicken reaches an internal temperature of 74°C (165°F) at the thickest point. Tent with foil near the end of cooking if needed to prevent the sauce from burning. Spoon sauce over the chicken before serving.