Preheat the oven to 450°f and slice the Baguette into one-inch crostinis.
Spread them evenly onto a parchment-paper-lined baking sheet and spray them with cooking spray. Flip them over, spray the other side, and then salt the top with Kosher salt.
Bake the crostinis for 10-15 minutes, watching them in the last few minutes to prevent overcooking.
Remove them from the oven and set aside until ready to serve.
Slice all of the onions and set them aside.
Add olive oil and butter to a Dutch oven or stewpan over medium-low heat.
Once the butter is fully melted, add the onions, stirring to thoroughly coat them in the oil and butter mixture.
Occasionally, stir the onions as they begin to caramelize, salt them with kosher salt, and then allow them to continue caramelizing.
Once the onions have been lightly caramelized, add the garlic, stir to incorporate, pour in the wine, deglaze the pot, and allow the wine to simmer for about 6 minutes.
Sprinkle in the chopped fresh thyme and give it all a good stir.
Add the shredded chicken to the onions, stirring to ensure even distribution.
Pour in the Beef Stock and Chicken Stock. Stir the French Onion Chicken Soup, add the bay leaves, bring to a boil, and then reduce the heat to low, simmering, uncovered, for 20 minutes.
While the soup simmers, shred your cheese and set aside until ready to serve.
Ladle the soup into the bowls of your choice, and top each bowl with your preferred amount of cheese, followed by a few crostinis.
Serve Hot, and Enjoy!