French Onion Pasta Casserole

INGREDIENTS

10 oz

fettuccine noodles, broken into thirds, cooked and drained

2 cups

cooked chicken, shredded

2 1/2 cups

beef broth

large onions (5-6 cups), halved and thinly sliced

1/4 cup

unsalted butter

1 tbsp

fresh thyme, minced

3 tbsp

all-purpose flour

2 cups

swiss cheese, grated

1/2 tbsp

balsamic vinegar

1/2 tsp

garlic powder

kosher salt and freshly ground pepper,

Topping:

1 cup

panko or seasoned breadcrumbs

2 tbsp

unsalted butter, melted