Heat the olive oil in a skillet over medium-high heat. Season the beef chuck pieces with salt and pepper, then brown them in batches for 4-5 minutes on each side. Transfer the beef to the slow cooker.

In the same skillet, add chopped onion and minced garlic. Sauté for about 3-4 minutes until they soften and become fragrant.

Deglaze the skillet by pouring beef broth and Worcestershire sauce, scraping up any browned bits. Pour this mixture over the beef in the slow cooker.

Sprinkle dried thyme and rosemary over the beef and broth. Add additional salt and pepper to taste.

Add diced potatoes and baby carrots to the slow cooker and stir gently to submerge them in the broth.

Set the slow cooker to low for about 8 hours or on high for 4 hours until the beef is tender.

Toast slices of bread until golden and crispy just before serving.

Spoon the Beef Manhattan generously over the toasted bread and garnish with freshly chopped parsley.