In a small bowl, beat cream cheese and butter until fluffy; beat in flour until blended. Cover and refrigerate for 1 hour or until easy to handle.
Shape dough into eight balls; press onto the bottom and up the sides of greased heart-shaped or regular muffin cups. In a small bowl, beat egg. Beat in brown sugar and vanilla until blended. Stir in walnuts. Spoon into cups.
Bake at 325° for 25-30 minutes or until lightly browned. Cool for 10 minutes before carefully removing from pan to a wire rack.