Step 1: Season the Beef - Pat the beef dry with paper towels first, because dry beef browns better and gives you a nicer flavor later. Sprinkle the stew beef evenly with the salt, pepper, onion powder, and garlic powder. I like to toss it all together with my hands so every piece gets a fair share of seasoning. This step may seem small, but it means the beef tastes good all the way through instead of just relying on the sauce.
Step 2: Sear the Beef - Heat the oil in a large skillet over medium high heat, then add the beef in batches. Give each piece a little room so it browns instead of steaming. Let it sear for about 2 to 3 minutes per side, just until you get that deep brown color. You are not trying to cook the beef through here. You are building flavor. I know it is tempting to skip this when life is busy, and you can, but when you have the extra few minutes, browning the beef makes the whole dish taste richer.
Step 3: Move the Beef to the Slow Cooker - Transfer the browned beef into the slow cooker, including any tasty bits you can scrape from the pan. Those little browned bits are flavor, and I am not in the habit of leaving flavor behind. Spread the beef out in an even layer so the sauce can settle around it while it cooks.
Step 4: Add the Broth and Flavor Makers - Pour the beef broth into the slow cooker over the beef. Add the butter, minced garlic, and Worcestershire sauce right on top. As the butter melts and the garlic warms, it works its way down into the broth and around the beef. This is where the kitchen starts smelling like you have been cooking something special all day, even though the slow cooker is doing most of the work.
Step 5: Cook Low and Slow - Cover the slow cooker and cook on LOW for 6 to 8 hours or on HIGH for 4 to 5 hours. I prefer LOW when I have the time because the beef gets extra tender and the flavor has more time to settle in. The beef is ready when it is soft enough to pull apart with a fork. Try not to lift the lid too much while it cooks. Every peek lets out heat, and slow cookers like to be left alone to do their thing.
Step 6: Cook the Egg Noodles - About 20 to 30 minutes before serving, cook the egg noodles according to the package directions until just tender. Drain them well. You do not want to add watery noodles to that beautiful sauce. I like cooking the noodles separately because they stay tender without turning mushy, which can happen if they sit in the slow cooker too long.
Step 7: Stir in the Sour Cream - Once the beef is tender, stir the sour cream into the slow cooker until the sauce looks smooth and creamy. Do this gently so you keep those lovely beef pieces mostly intact. The sour cream softens the richness of the butter and gives the sauce a cozy, creamy finish that clings to the noodles.
Step 8: Add the Noodles and Finish - Add the cooked egg noodles to the slow cooker and gently stir until everything is coated in the garlic butter sauce. Let the dish sit for 5 to 10 minutes before serving. That short rest helps the sauce thicken a little and gives the noodles time to soak up flavor. Sprinkle the parsley over the top and serve it warm, preferably in big bowls with everyone gathered around.