Cut the cabbage into wedges, season with salt, and sear on both sides in plenty of olive oil until golden.
Thinly slice the onions, season with salt, and sauté in olive oil or butter until soft. Set aside.
Layer the cabbage and onions in a casserole dish or cast-iron skillet. Pour over the stock & cream (about 1").
Add cheeses, thyme, salt, and pepper.
(Optional) Top with bread crumbs.
Roast at 200 °C for 20-30 minutes, until bubbly and golden on top.
