Pour the milk into a small bowl and place the bread on top. When most of the milk has been absorbed by the bread (about 3 - 4 minutes) add the onion, beef, egg, parsley, ketchup, hot sauce, salt, and pepper. Mix with your hands until no chunks of bread are visible.
Pat the mixture into a small casserole dish and bake for 1 hour.
Remove from the oven and cool for 10 minutes. Carefully drain the liquid from dish, making sure not to lose the loaf to the sink. Serve in slices.