You asked for a simple onion soup recipe you got it with this version.  Not only is it easy to make but it combines the rich taste of the broth, cheeses and French bread along with the flavorful onions to make a super satisfying dish.

Ingredients
½ cup unsalted butter
2 Tbs. olive oil
4 cups sliced onions
4 (10.5 ounces) cans of beef broth
2 tsp. dry sherry (optional)
1 tsp. dried thyme
4 slices French bread
4 slices Provolone cheese
2 slices Swiss cheese, diced
¼ cup grated Parmesan cheese

Instructions
Melt the butter with olive oil in an 8-quart stockpot on medium heat.  Add onions and continually stir until tender and translucent.  Do not brown onions.
Add beef broth, sherry, and thyme.  Season with salt and pepper, and simmer 30 minutes
Heat the oven broiler
Ladle the soup into oven-safe serving bowls and place one slice of French bread on top of each (bread can be broken into pieces).  Layer each slice of bread with a slice of provolone, ½ slice Swiss and 1 tablespoon Parmesan cheese.  Place bowls on a cookie sheet and broil in the preheated oven until cheese bubbles and browns slightly.

Thanks to www.allrecipes.com