Pat the beef top round roast dry with paper towels.
In a small bowl, combine kosher salt, black pepper, garlic powder, onion powder, smoked paprika, dried thyme, and dried rosemary.
Rub the seasoning mixture evenly all over the roast.
Heat olive oil in a large skillet over medium-high heat.
Sear the roast on all sides until browned, about 3-4 minutes per side.
Transfer the seared roast to the slow cooker.
Pour beef broth and Worcestershire sauce around the roast in the slow cooker.
Cover and cook on low for 8 hours, or until the beef is tender and easily sliced.
Remove the roast from the slow cooker and let it rest for 10 minutes before slicing thinly against the grain.
Serve the sliced roast beef warm or chilled for deli-style sandwiches.