3 tablespoons olive oil
2 tablespoons whole-grain mustard
1 tablespoon chopped fresh thyme
1 tablespoon apple cider vinegar, divided
3/4 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
1 pound peeled cubed butternut squash (about 3 cups)
1 pound parsnips, peeled and cut into 1-in. pieces (about 2 1/4 cups)
1 pound Brussels sprouts, trimmed and halved
8 ounces small Yukon Gold potatoes, halved
Preheat oven to 450°F.
Combine oil, mustard, thyme, 2 teaspoons vinegar, salt, and pepper in a bowl, stirring with a whisk.
Combine butternut squash, parsnips, Brussels sprouts, and potatoes in a large bowl.
Add mustard mixture to squash mixture; toss to coat.
Spread vegetable mixture in a single layer on a foil-lined baking sheet coated with cooking spray.
Bake at 450°F for 35 minutes or until browned and tender, stirring gently with a spatula after 25 minutes.
Drizzle with remaining 1 teaspoon vinegar; toss.