Adjust oven rack to upper position and preheat the oven to 400 degrees.
Cut the brussels sprouts in quarters and toss in a bowl with 2 tablespoons olive oil and 2 teaspoons kosher salt. Cover 2 large rimmed baking sheet with foil and spread the sprouts out on the pans so that there's just a single layer without them overlapping each other.
Transfer pans to oven to roast side by side for 15-20 minutes, shaking the dish every 5 minutes until dark and caramelized. Watch cooking time since it can vary based on the size of the sprouts.
While roasting, in a small saucepan over medium heat, add 1 tablespoons of olive and red onion and sauté until tender (approximately 5 minutes). Stir in remaining ingredients for the brown sugar reduction and reduce until sugar dissolves and the sauce has thickened.
Remove from brussels sprouts the oven and place in a heat-resistant bowl or serving tray. Slowly add in the sauce and toss them, a little at a time, to ensure they stay nice and crispy.
Top with sliced, almonds, dried cranberries and orange zest.