In a bowl mix the olive oil, lemon juice, mustard, salt and pepper. Peel the garlic and crush with a knife. Add to the marinade.

Place the chicken in a ziplock bag and pour the marinade over. Marinade at least 4 hours or overnight in the fridge.

Remove the chicken breasts from the marinade.

Heat a pan and add olive oil.

Grill the chicken on both sides. Season with salt and pepper.