This is probably the best comfort food on a cold day, a great way to stave off the anxiety of a looming dark and stormy night, and assurance to bring rosy cheeks and smiles to all. Most of the time, onion soup can just be whipped up by browning chopped onions and adding broth, but when you are in need of a severe antidote to extreme weather, I recommend the gratinée.
For two bowls, chop one large onion and bring it to a nice golden brown color, but without burning, in a pot on medium heat with one tbsp olive oil and one tbsp butter, 1/2 tsp sugar, a bay leaf, thyme, a tsp parsley. Be patient, stir often. When the onion has a nice honey brown color, add 2 tbsp flour (tapioca flour is nice) and stir in for 3 minutes (starting a light roux). Add 1/4 cup Macon or another dry white wine, and 1/4 cup Beaujolais or another light red, a sprinkle of Worcester sauce, salt and pepper and 2 cups beef broth and one cup water. Reduce by roughly one cup of liquid simmering gently for some time. The onions should be tender and the broth a little thicker by now. Throw out the bay leaf.
Pour into bowls that can go in the oven at a fairly high temperature. Do not fill the bowls more than 3/4. Add two thin slices of toasted baguette on each bowl and cover generously with grated Gruyère cheese. Brown the cheese in the oven.
This is a fairly rich soup as it is, it has a creamy texture but no cream, and I do not use very much butter at all contrary to some traditional French chefs.