In a medium bowl, combine flour, garlic powder, onion powder, salt, and black pepper to create a flavorful coating. Toss the beef stew meat in this mixture until well coated.

In a large skillet over medium heat, melt a couple of tablespoons of butter until bubbly. Add the coated beef and sear for 3-4 minutes on each side, or until browned. Transfer the beef to the slow cooker and set aside.

In the slow cooker, layer the sliced yellow onions evenly over the browned beef. Pour in the beef stock and sprinkle the French onion soup mix on top, followed by adding the bay leaf and dried rosemary. Gently stir to combine.

Cover the slow cooker and set it to low heat, allowing it to cook for 8 hours.

In the last 30 minutes of cooking, add the cubed cream cheese and sour cream directly to the slow cooker. Stir gently until fully melted.

While the beef mixture finishes cooking, bring a large pot of salted water to a boil. Cook the egg noodles according to package instructions for 7-8 minutes until al dente. Drain the noodles thoroughly.

Once everything is cooked, gently combine the creamy beef mixture with the drained egg noodles in the slow cooker. Toss until the noodles are coated in the sauce. If desired, top with crispy French fried onions.