1. Heat the oven to 400 degrees F. Unfold the pastry sheet on a lightly floured surface. Cut the pastry sheet into 25 (about 2-inch) squares.
2. Spoon about 2 teaspoons cheese in the center of each pastry square. Top each with about 1/2 teaspoon chutney and about 1/2 teaspoon walnuts. Brush 2 opposite pastry corners with water. Fold the pastry corners up over the filling and overlap slightly at the top, forming an open-ended "envelope", and press to seal. Place the filled pastries onto 2 baking sheets.
3. Bake for 15 minutes or until the pastries are golden brown. Sprinkle the pastries with the thyme before serving, if desired.