This is a different take on onion soup.  You have most likely had French onion soup, now try Italian.  You can find more Italian recipes in How to cook Italian by Guilano Hazan.

1 1/2 lbs. sweet yellow onions
2 Tbsp. extra virgin olive oil
1 Tbsp. butter
Salt
Freshly ground black pepper
1/3 C. dry white wine
3 C. homemade beef broth
4 slices crusty Italian bread
2 oz. pecorino cheese

Peel and thinly slide the onions crosswise. Put them in a soup pot with the olive oil and butter and season with salt and pepper. Place over medium-high heat and cook, stirring often, until the onions begin to brown, about 5 minutes. Lower the heat to medium-low and continue cooking until the onions are wilted completely and have started caramelizing, about 30 minutes.

Raise the heat to medium-high and add the wine. Let it bubble away until you no longer smell the alcohol. Add the broth and bring to a boil. Reduce the heat to low, cover the pot, and cook for 45 minutes.

When you are ready to serve, roast the bread slices and put one in each of the 4 soup bowls. Ladle the hot soup over the bread. Using a vegetable peeler, shave thin slices of the cheese over each serving. Serve at once.