01 -
Set your oven to 450°F and let it preheat. Pop some parchment paper onto a big baking tray and keep it ready.
02 -
Cut the cabbage into six pieces, each about 3/4-inch thick, holding onto the base. Lay them flat on the prepped tray. Brush with olive oil and season generously with salt and pepper.
03 -
Bake those cabbage rounds for 15 to 20 minutes. Watch for crispy, golden edges.
04 -
While the cabbage cooks, shred the cheese. Chop up the scallions super fine. Slice the corned beef into thin, 1/2-inch strips.
05 -
Spread about 1 teaspoon of mustard onto each roasted cabbage slice. Layer on the corned beef and sprinkle with grated cheese. Return to the oven for 5 minutes to melt the cheese and warm everything.
06 -
Scatter the chopped scallions over the top, then dish it up while it's still hot.