Preheat your oven to 350°F (175°C).

In a medium mixing bowl, combine 1/2 pound of ground beef, 1/4 cup chopped onion, 1/4 cup cracker crumbs, salt and pepper to taste, and 1/4 of the cream of mushroom soup. Mix until just combined without overworking the meat.

Using an ice cream scoop, portion the meat mixture evenly into six greased muffin tins, filling each nearly to the top to allow for slight expansion.

Bake in the preheated oven for approximately 30 minutes or until the meat is fully cooked through (check by cutting one muffin in half; there should be no pink remaining).

Transfer the muffins onto a cooling rack and let them rest for a few minutes.

Meanwhile, prepare the mushroom gravy by combining the remaining cream of mushroom soup with 1/4 cup water and 1 teaspoon Worcestershire sauce in a small saucepan. Warm over low heat, stirring occasionally until smooth and heated through.

To serve, place the meat muffins on plates and generously spoon the warm mushroom gravy over the top.