Step 1: In a small saucepan over medium heat, melt the butter and add the diced peaches, brown sugar, 1 teaspoon of cinnamon, and nutmeg.
Step 2: Cook the peaches for 5-7 minutes until they soften. Stir in the cornstarch and cook for another minute until the liquid thickens into a syrup. Remove from heat and let the filling cool completely.
Step 3: Preheat your oven to 400°F (200°C) and generously grease a 12-cup muffin tin.
Step 4: On a lightly floured surface, roll out the puff pastry sheets and cut each sheet into 6 long strips (12 strips total).
Step 5: Spread a thin layer of the cooled peach filling along each strip of pastry, leaving a small margin at the edges.
Step 6: Carefully roll each strip tightly like a jelly roll and place them upright into the prepared muffin tin cups.
Step 7: Bake for 22-25 minutes or until the peach pie cruffins are puffed and a deep golden brown.
Step 8: While the cruffins are baking, mix the granulated sugar and remaining cinnamon in a small bowl.
Step 9: Remove the cruffins from the oven and, once cool enough to handle but still warm, roll them in the cinnamon sugar mixture before serving.