Preheat oven to 425°F (220°C). Heat olive oil in a large oven-safe skillet over medium-high heat. Season cabbage wedges with salt and pepper, then sear cut-side down for 3–4 minutes per side until deeply golden. Transfer to a plate.
Reduce heat to medium. In the same skillet, add onion and cook 4–5 minutes until soft. Stir in garlic and cook 30 seconds until fragrant.
Add tomato paste and cook 1–2 minutes to deepen flavor. Stir in Italian seasoning, red pepper flakes, and sun-dried tomatoes. Pour in plant milk, scraping up browned bits. Simmer 3–5 minutes until slightly thickened. Season to taste.
Nestle seared cabbage wedges back into the skillet. Spoon sauce over each wedge and sprinkle evenly with vegan parmesan.
Transfer skillet to the oven and bake 15 minutes until cabbage is tender and sauce is bubbling. Broil 2–4 minutes until lightly golden and melting. Serve warm.
