Bring a 4-quart pot of water to a rolling boil, and cook the noodles according to package directions.

While the water is heating up, coat a 12-inch nonstick skillet with cooking spray, and preheat over medium-high heat. Add the mushrooms, onion, and garlic, and cook, stirring frequently, for about 7 minutes, or until the onion is soft and the mushrooms are lightly browned. Transfer the mixture to a bowl and set aside.

Place the beef in the skillet, and cook over medium-high heat, stirring constantly to crumble, for about 4 minutes, or until no pink remains. Drain off any excess fat.

Stir the mushroom mixture into the beef. Sprinkle with the black pepper and flour, and cook, stirring constantly, for 2 minutes.

Stir the broth into the beef, and bring to a boil. Cook, stirring frequently, for 3 to 4 minutes, or until the mixture has thickened. Stir in the Worcestershire sauce.

Reduce the heat under the skillet to low, and wait until the mixture is no longer boiling. Slowly stir in the sour cream, and heat for a minute or 2, or just until hot.

Drain the noodles well, and divide among individual serving plates. Top with the Stroganoff, and serve immediately.