Heat a large skillet over medium-high heat and then add a little oil to it. Once the oil is hot, add the boneless chuck roast and sear it until it is browned on all sides. This should take about 4-5 minutes per side.

Place the browned roast into the bottom of the slow cooker. Sprinkle 1 tablespoon of dry onion soup mix over the roast and pour ½ cup of beef broth around the roast.

Cut the stick of butter into pieces and place them on top of the roast. Spread the can of cream of mushroom soup over the roast as well.

Cover the slow cooker with its lid and cook on Low for a total of 8 to 10 hours, or on High for 4 to 5 hours.

Two hours before the end of the cooking time, place the 1.5 pounds of potatoes, 1/2 pound of baby carrots, 1 cup of diced onions, and 8 ounces of sliced mushrooms on top of the roast.

Sprinkle 1 tablespoon of Italian seasoning over the vegetables and cover. Continue cooking the roast for the remaining 2 hours.

Once the cooking time is complete, turn off the slow cooker and let the tender beef roast rest for about 10 minutes. Serve your fork-tender chuck roast with the vegetables and gravy from the slow cooker.