Combine all marinade ingredients together in a small bowl.
Cut peaches in half, pit, and place in a sealable container. Pour in about half of the marinade, coating each peach half, and reserve the rest. Seal the container and set peaches in the fridge for at least an hour, or overnight to allow the marinade flavours to infuse.
Heat your grill or barbecue at medium-high heat.
Place the peaches on the hot grill, face-down for 5-7 minutes or until charred and slightly softened.
Place grilled peaches on serving plate and top with remaining marinade and whipped cream (optional). Enjoy immediately. Best enjoyed when fresh, but any leftovers can be stored in a sealed container in the fridge for up to two days.