What You'll Need:

• 2 large yellow sweet onions, halved and sliced
  
• 2 large red onions, halved and sliced
  
• 3 tablespoons butter
  
• 3 cups low-sodium beef broth
  
• 1 cup dry white wine
  
• 1 ounce cognac
  
• 1 bay leaf
  
• 4 sprigs thyme
  
• 4 slices bread
  
• 4 ounces gruyere or Swiss cheese
  
• 1 ounce parmesan cheese
  
• salt and pepper
  

Step by Step:

1. Peel and halve the onions, then slice.
   
2. Melt a tablespoon of butter in a large skillet over medium heat, then add all of the onions, alternating with the remaining butter and a pinch of salt so the onions release their moisture.
   
3. Cover and cook the onions until they are well caramelized and reduced considerably. This will take about an hour. Stir occasionally.
   
4. Once onions have reduced, stir in white wine, beef broth and cognac and raise heat enough to bring to a boil. Add the bay leaf and thyme and reduce to a simmer.
   
5. Meanwhile, cut circles out of the bread, tracing around an ovenproof bowl or dish that you will bake the soup in.
   
6. Place the bread circles on a baking sheet and toast them directly under the oven broiler.
   
7. Grate the cheese!
   
8. Remove the bay leaf and thyme sprigs and divide the onion soup into bowls, top with a bread circle and a portion of the cheese. Put the bowls on the baking sheet and set under the broiler just until the cheese has melted.
   
9. Serve immediately.