Step 1: Preheat your oven to 400°F (200°C) and generously grease a 12-cup muffin tin with butter or non-stick spray.
Step 2: In a small saucepan over medium heat, combine the diced peaches, brown sugar, cornstarch, cinnamon, and vanilla. Cook for 5-7 minutes until the peaches soften and the liquid thickens into a syrup. Remove from heat and let cool completely.
Step 3: On a lightly floured surface, roll out each puff pastry sheet into a large rectangle. Brush the surface lightly with melted butter.
Step 4: Spread the cooled peach filling evenly over the pastry sheets, leaving a small border at the edges.
Step 5: Roll the pastry sheets up tightly starting from the long side to create a long log.
Step 6: Use a sharp knife to cut each log in half lengthwise, exposing the layers of dough and fruit.
Step 7: Take each half-log and roll it into a spiral shape with the cut layers facing outward. Place each spiral into the prepared muffin tin.
Step 8: Bake for 22-25 minutes, or until the peach pie cruffins are puffed and deep golden brown.
Step 9: Allow to cool in the pan for 5 minutes before transferring to a wire rack. Dust with powdered sugar if desired and serve warm.