Make a gruyere with sheep milk or sheep/goat/cow blend and it will make a graviera. Really, it's a straight up gruyere recipe. heat to 92F, add meso blend (O or LD type), add propionic, add thermo blend (helveticus, bulgaricus, strep), add rennet, use 2-2.5x multiplier, cut to 5-6 mm curds, heat to 125F or so, drain, pack.