Preheat your oven to 425 degrees F. Line a large baking sheet with parchment paper or foil.

Trim the brisket of excess fat and pat it dry with paper towels.

In a medium bowl, combine paprika, brown sugar, chili powder, salt, garlic powder, chipotle pepper, black pepper, onion powder, dried thyme, and cayenne pepper. Reserve 1 tablespoon of this spice rub for the barbecue sauce.

Apply the remaining spice rub all over the brisket. Make sure to cover both sides evenly.

Let the seasoned brisket sit at room temperature for 30 minutes or refrigerate it for up to 24 hours for marinating.

Place the brisket on the baking sheet and bake at 425 degrees F for 30 minutes to sear the meat.

While the brisket sears, prepare the barbecue sauce by combining ketchup, molasses, packed brown sugar, blackberry preserves, apple cider vinegar, mesquite liquid smoke, and reserved spice rub in a bowl. Whisk until smooth.

Remove 1/2 cup of the barbecue sauce and set aside. In the slow cooker, add water, Worcestershire sauce, reduced-sodium soy sauce, and beef bouillon. Whisk these ingredients with the reserved barbecue sauce.

Carefully place the seared brisket into the slow cooker with the liquid mixture. Cover with the lid.

Cook on LOW for 8 to 10 hours, flipping the brisket halfway through.

When the brisket is very tender, remove it from the slow cooker and place it on the baking sheet.

Brush the top of the brisket with the remaining homemade barbecue sauce.

Broil the brisket for 5 to 10 minutes until the sauce caramelizes. Watch it closely so it does not burn.

Simmer any leftover barbecue sauce in a small pan to warm through before serving. Slice the brisket across the grain and spoon warm sauce over the slices.