Bake for 20 minutes. Remove from oven & scatter remaining cheese on top. Return to oven for a further 3-5 minutes, or until cheese has melted. If desired, pop under the oven broiler for a short time to brown cheese a bit. Remove from oven. Allow to stand a couple of minutes, then loosen from pan and slice focaccia on to a cooling rack. While warm, top with a sprinkling of flaky salt & a scattering of a few fresh thyme leaves.