Spray a 6-quart (or larger) slow-cooker with nonstick cooking spray.
Pierce both sides of the brisket, about 3-4 inches apart, with a fork.
Generously sprinkle the entire brisket with garlic salt, onion powder, seasoned salt, paprika and black pepper.
In a medium bowl, whisk together liquid smoke, Worcestershire sauce, soy sauce and chicken stock.
Cut the brisket in-half, crosswise, so it fits in the slow-cooker.
Place half the brisket in the slow-cooker, fat-side up, and pour half the liquid mixture over the brisket half.
Add the other half of the brisket to the slow-cooker, fat-side up and pour the remaining half of the liquid mixture over the top portion of brisket.
Cover and set the slow-cooker to LOW. Cook 6 hours and flip-flop the positions of the brisket pieces (put the bottom portion on top and the top portion on the bottom).
Cover and cook an additional 3-5 hours or until brisket is fork-tender. It should be tender enough to cut with a fork.
Transfer the brisket from the slow-cooker to a large pan and cover it with foil. Let it cool to touch and refrigerate overnight. Spoon the sauce/cooking juices into a separate dish, cover and refrigerate overnight.
The next day, take the solidified fat off the pan juices and discard. Save the remaining pan juices for spooning over the brisket, if desired.
Slice the brisket to desired thickness, place in a serving dish, cover with and heat. Serve warm.