1. Slice 5-6 cups of onions (more if you really like a more bulky soup or less if you like it more liquidy)*Use white onions or at least a non-sweet onion (definitely not Vidalias, etc) or the soup will be weirdly sweet and not so delicious....
2. Put 2 1/2 tbsp of butter and 2 tbsp olive oil in a large pot, cook onions over medium heat for about 15-25 minutes covered until onions are clear and softened.
3. Add 1/2 tsp each of sugar (to help carmelize the onions) and salt.
4. Cook an additional 30 minutes or so on medium-high heat until onions are browned, stirring frequently.
5. Add about 7-8 cups beef stock/broth, along with 1/2 tsp pepper, 1/2 tsp Italian seasoning, and a bay leaf. (You can add additional seasonings while it simmers - just try it because too much makes it a weird herb soup and too little makes it kind of bland.)
6. Let simmer for 30 minutes or so, but don't let it get to a rolling boil.
7. If you want to add croutes and cheese, slice French bread in 1- 1 1/2" slices and lightly brush olive oil on each side. Place in a 325 degree oven for about 20-30 minutes until they get crusty.
8. Add a croute or two and parmesan or mozzerella cheese on top of a bowl of soup and put it in the oven for 30 min. and broil to brown the cheese.
Side note: I know this recipe looks long and scary, but it's pretty simple. It's basically Julia Child's recipe, although she uses less stock and adds wine. I'd just rather not, so I added the stock and she also uses sage instead of Italian seasoning. You certainly could skip 7 &8 and just dip toast in the soup or eat alone. Don't forget the cheese, though. It makes it so gooey and awesome. It is a little time consuming, but so worth it. It's even better heated up the next day, and freezes really well.