Toss the beef cubes in a bowl with flour, salt, and pepper until evenly coated.
Heat olive oil in a large skillet over medium-high heat and sear beef in batches until browned on all sides, then transfer to the slow cooker.
Add potatoes, carrots, onion, and garlic to the slow cooker.
In a separate bowl, whisk together beef stock, Worcestershire sauce, thyme, and rosemary, then pour the mixture over the contents of the slow cooker.
Tuck the bay leaf into the liquid.
Cover and cook on low heat for 7 to 8 hours or high heat for 4 to 5 hours until the beef is fork-tender.
Remove the bay leaf and stir gently before serving.