01 - Combine smoked paprika, garlic powder, onion powder, chili powder, ground cumin, black pepper, kosher salt, and brown sugar in a small bowl and mix thoroughly.
02 - Pat the brisket dry with paper towels and apply the spice rub evenly over all surfaces.
03 - Whisk together ketchup, apple cider vinegar, brown sugar, Worcestershire sauce, Dijon mustard, molasses (if using), liquid smoke (if using), beef broth or water, garlic powder, onion powder, black pepper, and salt until smooth.
04 - Place the brisket in the slow cooker fat side up, pour the BBQ sauce evenly over the meat ensuring thorough coverage.
05 - Cover the slow cooker and cook on LOW setting for 8 hours or until the brisket is very tender.
06 - Remove brisket from the cooker and allow it to rest for 10 minutes to redistribute juices.
07 - Slice or shred the brisket against the grain for optimal tenderness.
08 - Skim excess fat from remaining sauce in slow cooker and serve brisket topped with sauce.