Preheat the oven to 450ºF and line 2 cookie sheet (sheet pans) with parchment paper.
While the oven heats prepare the veggies. Cut the ends off the onion and peel away the tough outer layer. Cut the onion in half from the top to the bottom and lay each half flat side down on the cutting board. Cut them in half again, then turn the onion 90º and slice across it into 1/4″ slices (see picture above).
Cut both ends off the delicata squash and cut it in half lengthwise. Scrape out the seeds and cut each half in half again to create quarters lengthwise. Cut across the quarters to create 1/4″ slices.
Remove the ends and peel the carrots before thinly slicing them.
Cut off the fronds and tough outer stalks of the fennel, you can use these for another purpose like soup. Cut out the core and cut the fennel into 1/4″ thick slices.
Toss all the veggies together in a large bowl. From here you can roast them anyway you’d like, my favorite is to roast 1 pan with the spices listed above, and I roast the other pan plain with 2 tablespoons oil and 1/2 teaspoon sea salt.
Either way, divide the veggies onto the 2 lined cookie sheets and season accordingly.
Roast for 20 minutes, or until the veggies are tender and caramelized. Serve immediately with your choice of side dish.
Each pan makes approximately 4 cups of veggies, although they will shrink a bit after they’ve been refrigerated. I store my extra pan of veggies in a 1-quart mason jar for use throughout the week.