My favorite way to cook a pot roast is to take a nylon oven bag, toss in a chuck roast, and add peeled sliced potatoes (chunks), carrot pieces, and a few medium onions. Pour in a can of low or no sodium beef broth, and cook at 325 for 3 1/2 hours. I simply love the way the beef flavor passes to the potatoes, carrots, and onions. You can flavor this with garlic and ground pepper too. A salad on the side makes a full meal. This would cook well in the Pyrex pan, and the bag keeps the mess away from the glass so cleanup is easy.