In a large skillet, heat olive oil over medium-high heat. Season the beef pieces with salt and pepper, then brown them in batches for about 4-5 minutes on each side. Transfer the browned beef to the slow cooker.
In the same skillet, add the chopped onion and garlic, sautéing for about 3-4 minutes until softened. Pour in the beef broth and Worcestershire sauce, scraping up any browned bits from the bottom of the skillet.
Add the thyme, rosemary, and additional salt and pepper to the broth mixture. Pour this over the beef in the slow cooker.
Add the potatoes and baby carrots to the slow cooker, stirring gently to combine.
Cover and cook on low for 8 hours or on high for 4 hours, until the beef is tender and the vegetables are cooked through.
When ready to serve, toast the bread slices until golden brown. Serve the beef and vegetables over the toasted bread, garnished with fresh parsley.