Place 2 racks in the oven as close to the center as possible with at least 4" space between them. Preheat oven to 450 degrees and spray 2 baking sheets with cooking spray and set aside.
Wash, peel, seed and cut vegetables into appropriate sizes. (Avoid deviating too much from the indicated cut sizes as the cooking time for each vegetable varies depending on its size.)
Place the chopped vegetables in a large bowl, drizzle with olive oil and toss to coat. Add the rosemary, salt and pepper, and toss to coat once again. Divide the vegetable medley evenly between the 2 prepared baking sheets and arrange into an even layer.
Bake 40–45 minutes, tossing the vegetables every 15 minutes. The cooking time may vary slightly based on the size of the veggies, so roast until each vegetable is tender and the edges are slightly browned. Remove from oven, transfer to a serving dish and enjoy!
The size of the cut vegetables will seem large at first, but remember, they shrink while roasting. Follow the instructions and they’ll come out slightly firm on the inside and roasted beautifully brown on the outside!
Notes
Experiment with different seasonings and vegetables to find your favorite combination!