Line cupcake tin with liners. Place a vanilla wafer at the bottom of each liner.
Gently beat cream cheese, sugar and vanilla until smooth using an electric mixer. Gradually beat in fat-free yogurt, egg whites and flour. Do not over beat. Pour into cupcake liners filling half way.
Top each with 1 tbsp of the pumpkin butter. Using a toothpick, swirl the pumpkin butter into the cream cheese mixture for a marbling effect.
Bake 25 minutes or until center is almost set. Cool to room temperature. Chill a few hours in the refrigerator before serving.