Preheat your oven to 425°F and line two large sheet pans with parchment paper. I do two pans instead of one because crowding vegetables steams them instead of roasting them, and that's the mistake that kills this whole dish.

Toss all your cut vegetables—carrots, parsnips, sweet potatoes, Brussels sprouts, and red onion—into a large bowl with olive oil, salt, pepper, rosemary, and thyme. Use your hands to coat everything evenly so every piece gets the herb mixture.

Spread the vegetables across both sheet pans in a single layer with space between pieces. This open arrangement lets hot air circulate, which browns the bottom and edges instead of steaming the middle.

Roast for 35-40 minutes, stirring halfway through so the vegetables cook evenly on all sides. You'll know they're done when the edges are dark brown and the insides feel tender when you pierce them with a fork because that browning is where the flavor lives.

Remove from the oven and scatter toasted pumpkin seeds and parmesan cheese over the warm vegetables while they're still hot. The heat slightly softens the cheese and toasts the seeds' flavor even more.

Taste one piece before serving and adjust salt if needed because some ovens run hotter and vegetables lose moisture at different rates. I always taste before the table sees it because that's the moment I can fix anything without announcing it.