In a medium bowl, stir together butter and cream cheese. Mix in flour until well blended. Cover and refrigerate 1 hour.
While dough chills, make filling. In medium bowl, whisk together egg, brown sugar, melted butter and vanilla. Stir in cranberries and pecans. Top with whole cranberries.
Preheat oven to 325 degrees F (160 degrees C). Roll the dough into 1 inch balls. Press the balls into the cups of mini muffin pans so that dough covers the bottom and sides. Fill each one with a generous teaspoon of filling.
Bake for approximately 30 minutes in the preheated oven, until edges of tarts are golden brown.