Preheat the oven to 375 degrees F (190 degrees C). Line mini muffin pans with paper liners.

In a medium bowl, stir together cream cheese, 1/2 cup butter, and flour until a dough forms. Roll into 1-inch balls and press into the bottom and up the sides of the prepared muffin cups.

In a small bowl, blend together egg, butter, vanilla, and brown sugar until smooth. Stir in walnuts. Spoon mixture into the muffin cups, filling each 3/4 full.

Bake in the preheated oven for 15 to 20 minutes, until crusts are golden.