Whisk together olive oil, mustard, honey, garlic, salt, pepper, and rosemary. Place chicken in a gallon-size Ziploc bag and pour in the marinade. The mixture will be pretty thick. Press out excess air, seal bag and then gently mash with hands until the marinade mixture evenly coats the chicken. Refrigerate at least one hour or up to 24 hours.

Preheat an outdoor grill to about 350 and cook chicken for 6-7 minutes per side or until the internal temperature registers 165F. Tent with foil and let rest for 5 minutes. Drizzle fresh lemon juice over the chicken and serve.