Preheat oven to 450 F degrees. Line a large baking sheet with parchment paper sprayed lightly with cooking spray. Set aside.
In a large mixing bowl, combine olive oil, mustard, vinegar, thyme, salt, pepper, rosemary and basil, and whisk. Add chopped squash, cauliflower, brussels and potatoes, stirring to coat.
Spread vegetable mixture in a single layer on prepared baking sheet. Bake for 20 minutes, stir gently, then bake another 15 minutes.
Serve garnished with minced parsley if desired.
