Start by cubing the chuck steak into bite-sized pieces, then slice the onions thinly to aid in caramelization. Mince the garlic to release its rich aroma. Gather all your ingredients and have them ready for a smooth cooking process.

In a large, heavy-bottomed pot, heat about two tablespoons of olive oil over medium-high heat until shimmering. Add the cubed chuck steak in a single layer, searing for 5–7 minutes until browned on all sides. Remove the beef and set it aside.

In the same pot, melt two tablespoons of butter over medium heat, then add the sliced onions with a pinch of salt. Cook the onions for about 25–30 minutes until they've caramelized and turned a rich golden brown.

Once the onions are caramelized, sprinkle in two teaspoons of brown sugar and one teaspoon of thyme. Stir in the minced garlic, Worcestershire sauce, Dijon mustard, and tomato paste along with a tablespoon of flour. Cook for an additional 2–3 minutes.

Pour half of the dry grape juice into the pot, using a wooden spoon to scrape up any browned bits stuck to the bottom. Return the seared beef to the pot.

Add 4 cups of beef broth along with two bay leaves, bringing everything to a boil. Once boiling, reduce the heat to low, cover, and let it simmer gently for about 90 minutes.

While the stew simmers, preheat your oven to 400°F (200°C). Slice the baguette into thick pieces, brush them with olive oil, and spread a thin layer of Dijon mustard. Top each slice with Gruyere and Parmesan cheese, and bake for about 10 minutes.

When ready to serve, remove the bay leaves from the stew, ladle into bowls, and top with cheesy bread slices. Optionally garnish with fresh thyme.