A hearty and flavorful casserole featuring tender beef tips, caramelized onions, and a creamy, cheesy topping.
Heat the olive oil in a Dutch oven over medium-high heat.
Ensure the oil is hot before adding the beef to achieve a good sear.
Season the beef cubes with salt and pepper, then brown them in the hot oil, working in batches. Remove and set aside.
Avoid overcrowding the pan to ensure even browning.
Melt the butter in the same Dutch oven over medium heat, then add the onions and cook until golden and caramelized.
Stir occasionally to prevent the onions from burning.
Stir in the garlic and flour, cooking for 2 minutes to form a roux.
Cook the flour thoroughly to avoid a raw taste.
Add the beef broth, Worcestershire sauce, bay leaves, and thyme. Return the beef to the pot and simmer uncovered for 1 hour.
Stir occasionally to prevent sticking and ensure even cooking.
Stir in the cream and simmer for an additional 30 minutes.
Simmer gently to avoid curdling the cream.
Preheat the broiler and transfer the beef mixture to a greased baking dish.
Ensure the dish is evenly greased to prevent sticking.
Top with toasted bread slices and sprinkle with mozzarella cheese. Broil until the cheese is melted and bubbly.
Watch closely to prevent the cheese from burning.
Garnish with fresh thyme and serve immediately.
Serve hot for the best flavor and texture.