Preheat the oven to 350 degrees F (175 degrees C). Line 18 muffin cups with paper liners.

Blend softened cream cheese and 1/2 cup butter or margarine in a mixing bowl until thoroughly combined. Add flour and mix well. Place in the refrigerator to chill.

Combine brown sugar and 1 tablespoon butter or margarine in a mixing bowl. Add egg and vanilla; blend well. Stir in pecans.

Pat chilled dough into the bottoms of the 18 paper muffin cups. Pour in filling, distributing evenly between all cups.

Bake in the preheated oven until filling is set, about 30 minutes.