Preheat oven to 425°F/ 218.3°C. Peel butternut squash, cut the top and bottom off, slice in half and remove the seeds with a spoon.
Trim the end off of the brussels sprouts, slice in half and remove any outer leaves that are browning or just old.
Cut the top off of the fennel bulb, slice it in quarters, and cut the core out from each quarter and discard. Chop the rest of the fennel quarters in halves or thirds.
Peel the beet root and chop it into large chunks as well.
Slice the onion into large chunks and place all in a large bowl or onto a sheet pan.
Mince rosemary and add it to the mix along with the olive oil, garlic powder salt and pepper.
Mix it all up and put onto a sheet pan. I like to line the pan with parchment for easier clean up, but it's not necessary.
Roast in your oven, rotating pan half way through for even cooking for 20 to 25 minutes or until things are starting to brown and are fork tender. You can switch to broil at 500°F/260°C for the last 5 minutes to get a little extra brown on them. No need to raise the pan as you normally would for broiling.