Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper. In bowl, toss Brussels sprouts with 2 tbsp (30 mL) olive oil. Arrange mixture in single layer on prepared baking sheet. Bake 10 to 12 min. until tender crisp; mixing sprouts on sheet halfway through to loosen leaves for added crispiness.
In bowl, toss panettone cubes with chorizo and 2 tbsp (30 mL) olive oil. Stir into sprout mixture on baking sheet. Bake another 10 to 12 min. until bread is golden brown and toasted.
Meanwhile, whisk together remaining oil, vinegar, mustard, salt, pepper and red onion. Drizzle over baking sheet mixture, add apple and toss to coat. Transfer to serving bowl or individual plates. Serve immediately.
Garnish with shaved Parmesan cheese.
Use any leftover as a stuffing for thick-cut pork chops or chicken breasts.