Preheat your oven to 350°F (175°C). Lightly grease a 6-cup muffin tin.

In a medium mixing bowl, combine ground beef, chopped onion, cracker crumbs, salt, pepper, and about 1/4 of the can of cream of mushroom soup. Mix thoroughly but don't overwork the meat.

Using an ice cream scoop or spoon, divide the meat mixture evenly among the six muffin cups, filling each nearly to the top.

Bake for approximately 30 minutes, or until the meat is completely cooked through with no pink remaining in the center.

While the meat muffins are baking, prepare the gravy. In a small saucepan, combine the remaining cream of mushroom soup with water and Worcestershire sauce. Heat over low heat, stirring occasionally until smooth and warmed through.

Allow the muffins to rest for a few minutes after removing from the oven, then transfer to serving plates.

Spoon the warm mushroom gravy generously over each muffin before serving.