Recipe from 5 Ingredients or Less Slow Cooker Cookbook by Stephanie O'Dea
Use a 6-quart slow cooker. Place the roast in the insert, and sprinkle with the salt and pepper. Heat the olive oil in a large skillet on the stovetop over medium heat. Add the mushrooms and cook, stirring, until they have browned completely and have shrunk in size. This will take longer than you think it should — don’t rush the mushrooms! Add the onion rings, and cook, stirring, until wilted and translucent. Pour the broth into the skillet, and remove from the heat.
If desired, pour the mushroom mixture into a large mixing bowl and set aside. Use the same skillet to brown all sides of the roast. Replace the roast in the insert and pour the mushroom gravy on top. Cover and cook on Low for 8 to 10 hours, or until the beef can be easily cut with the edge of a fork.