Preheat oven to broil, place oven rack in highest position.
On large baking sheet, place mushrooms, Brussels, squash and onion. Drizzle with oil and garlic butter. Season with salt and pepper. Mix to coat vegetables. Broil, stirring occasionally, until browned, 15-20 minutes.
Meanwhile, in saucepan of boiling water, cook pasta according to package directions. Reserve about 1 cup of pasta water. Drain pasta.
Return pasta to saucepan. Stir in butter and about ½ cup of reserved pasta water. Season with salt and pepper. Add roasted vegetables, balsamic vinaigrette and more pasta water to reach desired consistency. Sprinkle with Parmesan and oregano, if using.
Balsamic Vinaigrette. Mix 3 tbsp balsamic vinegar, 3 tbsp olive oil, 2 chopped garlic cloves, 2 tsp maple syrup, 1 tsp of dried oregano. Makes about ½ cup
