Prep the cabbage: Rinse cabbage and cut cabbage into large wedges, keeping the core intact so they hold together.
Sear the wedges: Heat olive oil in a large oven-safe skillet over medium-high heat. Sear cabbage wedges for 2–4 minutes per side, until charred. Remove and set aside.
Build the sauce: In the same skillet, melt the butter, then add the onion and sauté until softened. Stir in garlic, salt, pepper, Italian seasoning, and Cajun seasoning.
Make it creamy: Add cream cheese and chicken broth. Stir until smooth and creamy. Mix in the grated Parmesan. If the sauce feels thin, whisk in the cornstarch slurry and cook until thickened.
Bake: Return cabbage wedges to the skillet, spoon sauce over the top, and transfer to the oven. Bake at 350°F (175°C) for 50 minutes, until cabbage is tender.
Finish: Switch oven to broil on high for 5 minutes to brown the top.
Garnish & serve: Sprinkle with shredded Parmesan and fresh parsley before serving.