French Onion Soup Casserole

8 medium onions, sliced
5 Tbsp. butter, divided
2 Tbsp. all-purpose flour
Dash pepper
3/4 cup beef broth
1/4 cup sherry or additional beef broth
1-1/2 cups salad croutons
1/2 cup shredded Swiss cheese
3 Tbsp. grated Parmesan cheese

In a large skillet, saute onions in 3 Tbsp. butter until tender. Stir in flour and pepper until blended; gradually add broth and sherry. Bring to a boil; cook and stir for 3 minutes or until thickened. Transfer onto an ungreased 9" square baking pan.

In a microwave, melt the remaining butter. Add the croutons; toss to coat. Spoon over the onion mixture. Sprinkle with cheeses.

Broil 3-4" from heat for 1-2 minutes or until cheese is melted.