Layer the base. Add sliced onions and mushrooms to the bottom of your crockpot.
Add the beef. Place the stew meat on top. Season with a pinch of salt and pepper.
Flavor it up. Sprinkle in onion soup mix, paprika, and thyme. Add minced garlic and Worcestershire sauce.
Pour and dollop. Pour in the beef broth.
Spoon the condensed cream of mushroom soup over everything. Do not stir.
Slow cook. Cover and cook on Low for 7–8 hours or High for 4–5 hours, until the beef is fork-tender.
Thicken (optional). If you want a thicker sauce, stir in the cornstarch slurry. Cover and cook on High for 15–20 minutes until slightly thickened.
Make it creamy. Turn off the heat.
Stir in the cream cheese until melted, then fold in the sour cream. Adjust salt and pepper to taste.
Serve. Spoon over cooked egg noodles, rice, or mashed potatoes. Garnish with chopped parsley.