In a frying pan, saute‚ the onion and garlic in the oil for 5 minutes, or until soft. Add the cabbage and fennel seeds, stir well, and cover. Cook over medium-low hear until the cabbage is just wilted.
Preheat the oven to 425F. Place the pizza crust on a greased baking sheet, and top with the tomato sauce, then the cabbage mixture. Sprinkle with the Parmesan cheese. Bake for 15 to 20 minutes,or until the cheese is lightly browned.