In a large heavy skillet or Dutch oven over medium heat, cook chopped bacon lardons for 6 to 8 minutes until crisp and golden brown. Transfer bacon with a slotted spoon into the slow cooker insert, leaving rendered bacon drippings in the skillet.

Pat beef chunks thoroughly dry with paper towels. Season generously with kosher salt, black pepper, and dust with all-purpose flour. Increase skillet heat to medium-high.

Working in 2 uncrowded batches, sear beef chunks in hot bacon fat for 3 to 4 minutes per side until a deep, dark caramel crust forms. Transfer seared beef into the slow cooker.

Reduce heat to medium. Add tomato paste and minced garlic to the skillet drippings; sauté for 60 seconds until fragrant and brick-red.

Pour in 1 cup of the dry red wine, using a wooden spoon to vigorously scrape up all browned bits (fond) stuck to the bottom of the pan.

Pour the deglazed wine mixture over the beef in the slow cooker. Add remaining red wine, beef bone broth, sliced carrots, Worcestershire sauce, fresh thyme, rosemary sprigs, and bay leaves.

Cover slow cooker with lid. Cook on LOW for 7 to 8 hours (or on HIGH for 4 to 5 hours) until the beef chunks are ultra-tender and easily yield to the gentle press of a fork.

During the final 45 minutes of slow cooking, melt 2 tablespoons butter in a skillet over medium-high heat. Add halved cremini mushrooms and pearl onions; sauté for 8 to 10 minutes until deeply browned and caramelized.

Gently fold the sautéed mushrooms and onions into the slow cooker. Cover and cook for the remaining 30 minutes to marry flavors together.

Discard herb sprigs and bay leaves. Skim excess fat from the surface if desired. Garnish generously with fresh parsley and serve piping hot.