Begin by heating a large skillet over medium-high heat. Once warm, add the lean ground beef, diced yellow onion, and minced garlic. Cook this mixture for about 5-7 minutes, stirring occasionally, until the beef is evenly browned and the onion becomes translucent.

Sprinkle the all-purpose flour over the browned meat mixture and stir for about 1 minute to cook off the flour's raw flavor. Gradually pour in the beef broth while continually stirring. Add the dried minced onion flakes, onion powder, garlic powder, Worcestershire sauce, salt, and black pepper. Allow this flavorful mixture to simmer for another minute until everything is well combined and slightly thickened.

Reduce heat to low and stir in 1 cup of shredded cheddar cheese along with the sour cream. Mix until everything is well incorporated and the cheese has melted into the savory sauce.

Transfer the meat and cheese mixture into a baking dish, spreading it evenly. Add the diced russet potatoes and carrots. Gently mix everything together.

Sprinkle the remaining shredded cheddar cheese over the top. Cover the dish with aluminum foil and bake it in a preheated oven at 400°F for 30-35 minutes.

Once baked, carefully remove the casserole from the oven, then take off the foil. Sprinkle dried parsley on top, if desired. Serve warm.