I love onions, and especially French Onion soup. Being married to someone who doesn't like them means that I don't get to have a dish with a lot of onions in it very often, so when I do, I make it good. This recipe takes time to make, and amazes people when I don't use sugar to carmelize the onions. It's well worth the extra time.
For easiest slicing, first cut onions in half lengthwise, then set cut side down so they don't roll. Cut into thin slices.
In a Dutch oven or thick bottom pan, heat butter and oil over medium heat. Add onions, 1 teaspoon salt, and 1/2 teaspoon pepper and stir.
Cook, stirring occasionally, until onions begin to soften, about 10 minutes. Reduce heat to medium low and cook slowly, stirring occasionally, until onions are carmelized, about 1 hour 15 minutes in all.
After about 30 minutes of cooking, the onions should be a light golden brown. If they are not, adjust heat accordingly. 45 minutes later, oinions should be a deep brown. Dark, carmelized onions are the secret to good onion soup.
Stir flour into onions, bring to a bubble and then cook 2 or 3 minutes.
Slowly sir in stock, water and cognac.
Simmer, partially covered, about 15 minutes to blend flavors.
Taste for seasoning and add salt and pepper if needed.
Serve with bread and topped with cheese if desired.