Preparation

Step 1: Brown the Beef

1. Pat the beef chunks dry with a paper towel and season with salt and pepper.
2. Heat olive oil in a large Dutch oven or deep skillet over medium-high heat.
3. Add the beef in batches, searing each piece until golden brown on all sides (about 4-5 minutes per batch).
4. Remove the browned beef and set it aside on a plate.

Step 2: Caramelize the Onions

1. Reduce heat to medium and add butter to the pot.
2. Add the sliced onions, stirring frequently.
3. Cook for 15-20 minutes, or until onions become golden brown and caramelized.
4. Stir in the minced garlic and cook for another minute.

Step 3: Build the Flavorful Base

1. Sprinkle the flour over the onions and stir to coat. Cook for about 1 minute.
2. If using red wine, pour it into the pot and deglaze by scraping up any browned bits from the bottom. Let it simmer for 2-3 minutes.
3. Pour in the beef broth and stir well to combine.
4. Add fresh thyme if using, then return the browned beef to the pot.

Step 4: Simmer the Dish

1. Bring the mixture to a boil, then reduce heat to low.
2. Cover and let simmer for 45-60 minutes, or until the beef becomes fork-tender. Stir occasionally.

Step 5: Add the Cheese Topping

1. Preheat the broiler (or oven set to high heat).
2. Transfer the beef mixture to an oven-safe baking dish or leave it in the oven-proof pot.
3. Evenly sprinkle shredded Gruyère or Swiss cheese over the top.
4. Place under the broiler for 3-5 minutes, or until the cheese is melted, bubbly, and slightly golden.

Step 6: Serve and Enjoy

1. Remove from the oven and let cool slightly.
2. Garnish with fresh parsley, if desired.
3. Serve hot with toasted bread on the side for dipping into the rich, cheesy sauce.