You might find this recipe helpful because it does make that dense dark gravy. This is the way we make it in PA Diner Land.
REAL DINER POT ROAST
Get a big hunk of well marbled boneless or bone-in chuck roast, at least 3 lbs. Do not use wimpy lean sirloin, round or any other cut of meat. Fry 4-6 strips of bacon in a Dutch oven or deep heavy skillet with a lid big enough to accommodate the meat. Remove bacon and leave bacon fat in the pan. Sprinkle the roast with salt and pepper and dust lightly with flour. Heat bacon fat over medium-high heat. Add pot roast and let it cook and sizzle until deep brown on that side. Remove roast, swirl bacon fat around and return roast to pan to brown another side of it. Continue until all sides of roast are thoroughly browned. If the chuck is boneless, you can brown and cook a piece or two of marrow bone along with it. This almost-but-not-quite-burning is what will start the process for that melt in your mouth brown gravy.
When meat is browned, add 1 cup of water to the pan. Cover loosely and cook over medium-low heat until almost all water is evaporated. Turn the roast over; then add another cup of water and you can finally stir up those little browned bits. Add whatever vegetables you want; onions and carrots are traditional but you can also use garlic, turnips, leeks, etc. and continue cooking as before. Next time the water is almost dried up, turn both the roast and vegetables over. Repeat the cooking until almost dry, then adding a cup of water until the meat is fork-tender and ready to fall apart (Diners don’t do medium rare.). Remove the meat and set aside.
It’s up to you whether to remove the vegetables or as some places do, mash them with a potato masher right in the pan at this point. Add about 2 cups of beef stock and stir thoroughly, then turn heat up to high. Add salt and pepper to taste. Mix 2 Tbsp. of flour with 2/3 cup of water to form a smooth paste. When pan juice is boiling, pour the flour mixture into it through a tea strainer, unless you want authentic lumps. Continue boiling gently over medium heat for at least 5 minutes until gravy is thickened.
Hack the meat into chunky pieces, scoop out an ice-cream dipper of mashed potatoes, pour gravy over top and serve.
P.S. This is also the right stuff for hot roast beef sandwiches.