Preheat your oven to 325°F (163°C).

Generously season the beef chuck cubes with salt and black pepper. Heat 2 tablespoons of olive oil in a Dutch oven and sear the beef in batches for 5-7 minutes per batch, then remove and set aside.

In the same pot, add the diced pancetta and cook until crispy, about 4-5 minutes. Remove and set aside, keeping the drippings in the pot.

Add the yellow onion and sliced carrots, sauté for 8 minutes until softened. Stir in minced garlic and tomato paste, cooking for an additional minute.

Sprinkle flour over the sautéed vegetables and stir well, cooking for 2 minutes. Gradually pour in the red wine, scraping up browned bits. Add beef stock, stirring until smooth.

Return the browned beef and crispy pancetta to the pot with the bay leaf and thyme. Bring to a simmer, cover, and transfer to the oven for 2.5 to 3 hours.

In the last 30 minutes, sauté the pearl onions and halved mushrooms in 2 tablespoons of butter in a skillet until golden brown.

Add the sautéed pearl onions and mushrooms to the stew, allowing flavors to meld for the final half hour.

Remove from the oven, discard bay leaf and thyme. Adjust seasonings and serve hot, garnished with chopped parsley.