Brussels Sprout & Leek Gratin with Rosemary

Ingredients

• 1 ½ pounds Brussels sprouts
• 2 Tablespoons olive oil
• 3 leeks, tops removed, halved and sliced
• 4 cloves garlic, minced
• 1 ½ teaspoons Kosher salt
• ¼ teaspoon ground black pepper
• 2 teaspoons chopped fresh rosemary
• 2 Tablespoons all-purpose flour
• 2 ¼ cups nonfat milk
• 2 ounces grated romano cheese (about 2/3 cup)
• 1/8 teaspoon nutmeg
• 1 Tablespoon lemon juice
• ½ cup panko breadcrumbs
• 2 scallions, chopped