Using both dijon and seeded mustard blends perfectly with rosemary to create succulent chicken breast with a delicious sauce.
Preheat the oven to 200C / 392F and grease a small baking tray.
Pat dry the chicken breast and put in the baking tray. Combine all ingredients except the butter and whisk together in a small bowl.
Pour the sauce over the chicken and turn to coat evenly.
Place in the oven for 25 - 30 minutes, checking with a meat thermometer after 25 minutes. Remove once they reach 70 degrees C and let rest for 3 - 4 minutes.
While resting, put the 1 tablespoon of butter into the pan juices and whisk to combine.
Serve sliced chicken breast topped with mustard sauce, and accompanied by cauliflower mash or steamed broccoli tossed in butter.