Pat beef cubes dry and season generously with salt and pepper. Let rest at room temperature for about 30 minutes.

Melt 2 tablespoons butter in a large Dutch oven over medium-high heat. Cook bacon 6 to 7 minutes until crisp. Remove bacon and set aside, leaving fat in the pot.

Preheat oven to 325°F (163°C). Working in batches, brown beef cubes on all sides, about 3 minutes per side. Transfer browned beef to a bowl.

Melt 2 tablespoons butter in the pot. Add garlic, carrots, pearl onions, thyme, and bay leaves. Cook 6 to 7 minutes until onions are glossy.

Return beef and bacon to the pot. Add tomato paste and flour, stirring until no dry flour is visible. Pour in red wine, brandy, and beef stock. Bring to a simmer, cover, and transfer to oven for 1 hour 30 minutes.

While stew braises, melt remaining 2 tablespoons butter in a skillet. Add mushrooms, season with salt and pepper, and cook 10 minutes until browned.

Remove Dutch oven from oven, stir in mushrooms, and return to oven for 30 more minutes. Adjust seasoning and let rest 15 minutes before serving, garnished with parsley.