Cut the onions in half and chop off the ends. Remove the skins. Slice the onions widthwise thinly but not paper thin.

Place a dutch oven over medium heat. Add the oil and butter. Once hot, add the sliced onions, garlic, thyme, and bay leaves. Toss to coat in the fat. Lightly season with salt and pepper. Stir the onions occasionally to even cook the onions. Adjust the heat accordingly if it seems to be browning too quickly. This will take approximately 45 minutes to 1 hour.

Once your onions are soft and golden, Add the flour and stir to combine. Cook for one minute. Add the wine and stir until incorporated while scraping the bits off the bottom of the pot. Add the stock and turn the heat to high. Bring the soup to a boil then down to a simmer oven medium low heat. Simmer for one hour.

Preheat your broiler.

Ladle the soup into oven safe bowls. Top each with a slice of bread and a generous helping of grated cheese. Place it under the broiler for 2-3 minutes until golden brown.