Begin by heating a cast iron skillet or large frying pan over medium heat. Add the lean ground beef, seasoning it generously with salt, black pepper, garlic salt, and dried minced onion. Cook for about 7-10 minutes, breaking apart the meat with a spatula, until it's browned and no longer pink.

Once the ground beef is cooked through, lower the heat slightly and add sliced salted butter to the pan. Allow the butter to melt into the beef, stirring gently to combine.

Sprinkle all-purpose flour over the beef and melted butter, mixing thoroughly with a whisk or spatula, cooking this mixture for about 2 minutes until light golden brown.

Gradually pour in the whole milk while continuously stirring to avoid lumps. Keep the heat at medium-low and cook until the gravy thickens, about 5-10 minutes.

Once the gravy has thickened to your liking, spoon it generously over mashed potatoes, rice, or noodles and serve.