Press seams of puff pastry sheet together. Cut sheet into quarters and then each quarter into six pieces. Use a rolling pin to flatten each piece of pastry into a square shape. Place the squares into 24 greased mini muffin cups.
Put about 1/2 teaspoon of Brie, 1 teaspoon of apple butter and 1/2 teaspoon of chopped pecans into each muffin cup.