Balsamic Roasted Brussels Sprouts

Ingredients
1 16-oz. pkg. fresh Brussels sprouts
1 Small red onion, thinly sliced
5 Tbsp. olive oil, divided
1/4 Tsp. kosher salt
1/4 Tsp. freshly ground black pepper
1 Shallot, chopped
4 Tbsp. balsamic vinegar
1 Tbsp. chopped fresh rosemary
Directions
Preheat oven to 425°F. Combine Brussels sprouts and onion in medium bowl with 3 tablespoons of the olive oil, salt and pepper, tossing gently. Spread on lightly greased baking sheet; roast 25 to 30 minutes or until vegetables are tender and caramelized.
Meanwhile, sauté shallot in remaining olive oil in small skillet over medium-high heat 5 minutes or until tender. Add balsamic vinegar and cook 5 minutes more. Stir in rosemary and pour over Brussels sprouts