Preheat the Oven: Preheat your oven to 425°F (220°C). Line a large baking sheet with parchment paper or lightly grease it with a bit of olive oil.
Prepare the Vegetables: In a large bowl, combine the broccoli florets, cauliflower florets, sliced baby portobello mushrooms, baby carrots, chopped red bell pepper, and onion wedges.
Season the Vegetables: Drizzle the olive oil over the mixed vegetables. Add salt, fresh ground pepper, Italian seasoning, and garlic powder.
Arrange on the Baking Sheet: Spread the seasoned vegetables in a single layer on the prepared baking sheet. Make sure they are not overcrowded; this will ensure even roasting and a nice, crispy texture.
Roast the Vegetables: Place the baking sheet in the preheated oven and roast for 20-25 minutes. Halfway through, stir the vegetables to promote even cooking. Roast until the vegetables are tender and slightly caramelized around the edges.
Garnish and Serve: Once roasted to your desired level of doneness, remove the vegetables from the oven. If desired, sprinkle the vegetables with grated Parmesan cheese and chopped fresh parsley while they’re still warm for an extra burst of flavor.
Serve: Transfer the roasted vegetable medley to a serving platter and enjoy as a delicious side dish, or use them to top salads, grain bowls, or pasta for a hearty, veggie-packed meal.