In a large Dutch oven, melt the butter on medium heat. Once melted, add the oil. Add the sliced onions, leeks, and shallots.
Stir to coat with the butter and let cook down (covered with the lid slightly ajar) for about 15 minutes. Stirring to toss occasionally.
Add 4 of the sage leaves, minced garlic, sugar, salt and pepper. Toss to coat.
Let cook down covered with the lid slightly ajar, stirring every ten minutes for 50 minutes.
Add 1/2 cup of the wine, deglazing the pan. Let cook down until the liquid has been absorbed.
Add the broth, remaining wine, 3 sage leaves, and bay leaves.
Start heating the broiler on your oven at this time.
Bring to a boil, then turn heat down again to medium and let simmer for 10 to 15 minutes.
Slice a baguette in 3/4 inch slices, and toast 2 pieces per bowl of soup for 1 minute. Flip over and toast for another minute or so, until they JUST start turning brown.
Remove from broiler, and rub the more toasted side with the clove of garlic.
Place a teaspoon of brandy in the bottom of each soup cup.
Ladle the soup into the cups, place 2 pieces of baguette on top of each (give a slight dunking, if needed, to fit), top with 1/4 cup of Gruyere and 1/8 cup Asiago (per cup).
Place cups onto foil lined cookie sheet, pop back under the broiler for a few minutes until the cheese bubbles and just starts to brown.
Serve immediately with a warning that the soup AND bowl are hot!
Notes
Use a mandolin on thin setting to slice the onions, shallots, and leeks. Makes slicing go by quickly! Most recipes called for a sherry, but all I had was some Torres 5 Year Brandy, and it tasted wonderful.