Season both sides of the chuck roast with the onion powder, garlic powder, seasoned salt, and pepper.
Heat the olive oil in a large skillet over medium heat. Add the chuck roast and sear both sides until browned.
In your slow cooker, stir together the Coca-Cola, beef broth, au jus gravy mix, and sliced onion.
Add the chuck roast and baby carrots to the slow cooker.
Cover and cook on LOW for 8 to 10 hours or HIGH for 5 to 7 hours, until the roast is fork-tender and pulls apart easily.
Serve warm with the carrots and cooking liquid.
Notes
Chuck roast is ready when a fork slides easily into the meat and the beef pulls apart with very little resistance.
If the roast is still tough, continue cooking it. Slow cookers and individual roasts vary, so tenderness is a better final test than cooking time alone.
The roast does not need to be submerged in the cooking liquid.
Searing can be skipped if needed, but browning the roast first adds deeper flavor.
Store leftovers with some of the cooking liquid in an airtight container in the refrigerator for up to 4 days.