Preheat the oven to 400 degrees. Take out two baking sheets.Slice off the tough ends of the Brussels sprouts and pull off any yellow outer leaves. Slice them in half. In the bottom of a medium mixing bowl, add 2 tablespoons of the olive oil, all of the maple syrup and balsamic. Stir to combine and add in the Brussels sprouts. Season with salt and pepper and toss again to combine.Transfer the seasoned Brussels sprouts to one of the baking sheets and roast for 30 to 35 minutes, until crisp on the outside and tender on the inside. Shake the pan every 15 minutes to brown the sprouts evenly.Meanwhile, peel and spiralize the onions with Blade A. Place the onion noodles in the same large bowl used to toss the sprouts and drizzle with remaining oil (two teaspoons.) Season generously with salt and pepper and add them to the other baking sheet, trying not to overcrowd the noodles (the noodles will steam instead of roast if they’re overlapping.) Bake alongside the Brussels sprouts for 20 minutes or until cooked through and beginning to crisp, shaking the pan once to make sure the noodles cook.Toss the finished Brussels and onion noodles together and serve with an extra pinch of kosher salt, for an extra salty kick. Garnish with pecans if desired.