Preheat oven to 375*
Remove the outer leaves of the cabbage and discard. Place the bottom of the cabbage flat onto a cutting board and slice cabbage to 1 inch thick rounds.
Lay cabbage steaks onto a large greased casserole dish.
Evenly drizzle olive oil and balsamic vinegar.
Season with salt and pepper to taste.
If using mushrooms evenly spread on top of seasoned cabbage then drizzle with more olive oil and season with salt and pepper.
Bake in oven for 30 minutes until cabbage is tender and lightly chard on the outside.