Preheat oven to 425°F. Line a large rimmed baking sheet with foil.
Trim stem off cabbage. Slice the cabbage horizontally into 4 (1-inch-thick) steaks. Place the steaks on the prepared baking sheet.
Brush both sides of the cabbage steaks with olive oil. Sprinkle both sides evenly with onion powder, ½ teaspoon pepper, paprika and salt. Roast until tender and browned, about 45 minutes, flipping halfway through.
Meanwhile, prepare sun-dried tomato cream sauce: Combine sun-dried tomatoes, tomato oil, shallots and garlic in a medium saucepan. Cook over medium heat, stirring occasionally, until the shallots are softened, about 3 minutes.
Add broth and wine; bring to a simmer over medium heat. Simmer, stirring occasionally, until reduced by half, about 15 minutes.
Whisk in cream; bring to a simmer over medium heat. Simmer, undisturbed, until the sauce thickens slightly and coats the back of a spoon, 5 to 8 minutes.
Remove from heat; whisk in Italian seasoning, salt and pepper until fully combined.
Place 1 cabbage steak on each of 4 plates; spoon sauce onto the steaks. Garnish with parsley, if desired.
