1/2 (17.3 ounce) package Pepperidge Farm® Puff Pastry Sheets
3/4 pound Brie cheese, well chilled and rind removed
1/3 cup walnuts, finely chopped
1 tablespoon packed brown sugar
1 tablespoon Dijon-style mustard

1. Thaw the pastry sheet at room temperature for 40 minutes or until it's easy to handle. Heat the oven to 400 degrees F.
2. Unfold the pastry sheet on a lightly floured surface. Roll the sheet into a 14-inch square. Cut into 36 (2 1/4-inch) squares. Gently press each square into each section of 3 (1 3/4-inch) mini muffin pans.
3. Cut the cheese into 36 pieces, about 1 x 1/2-inch thick. Stir the walnuts, brown sugar and mustard in a small cup. Spoon about 1/4 teaspoon of the sugar mixture on the bottom of each pastry square. Top each with a piece of cheese.
4. Bake the tartlets for 15 minutes or until golden. Let cool for 5 minutes on a wire rack. Serve warm.