Begin by combining all the ingredients for the spice rub in a small bowl. Mix them thoroughly until they are well blended.
Measure out 2 tablespoons of the mixed spice rub for immediate use, and store the remaining mixture in a sealed container for later.
Preheat your oven to 275 degrees Fahrenheit.
Take the chuck roast and generously apply 1–2 tablespoons of the spice rub all over its surface, ensuring even coverage.
Rub the spice mixture into the meat using your hands, making sure to coat all sides evenly.
Place a roasting rack on a sheet pan and transfer the seasoned roast onto the rack.
Bake in the preheated oven for approximately 3 hours.
Once done, remove the roast from the oven and cut it into 1" cubes.
Spread the meat chunks evenly on a baking sheet.
Cover the meat with barbecue sauce and distribute the pats of butter over the top.
Return the sheet pan to the oven and increase the temperature to 450 degrees Fahrenheit.
Bake for an additional 30 minutes, or until the edges of the meat are deeply seared and crispy.
Halfway through cooking (around the 15-minute mark), stir the meat to ensure even browning.
Once done, remove from the oven and serve your homemade poor man’s burnt ends. Optionally, serve with extra barbecue sauce according to preference. Enjoy your delicious creation!