Preheat the oven to 400°F (200°C).
Roll out the puff pastry just enough to fit the bottom of a 10-inch oven-safe skillet. Press it gently into the base and slightly up the sides. Refrigerate while you prepare the filling.
1 sheet puff pastry
In a small bowl, mix together the cinnamon, brown sugar, and cornstarch.
⅓ cup brown sugar, 2 teaspoons cinnamon, 1 Tablespoon cornstarch
Sprinkle half of the cinnamon-sugar mixture evenly on the bottom of the puff pastry.
Arrange the peach slices over the spiced base in overlapping circles or rows.
4 –5 medium peaches
Sprinkle the remaining cinnamon mixture evenly over the peaches.
Fold the edges of the puff pastry slightly over the filling to create a rustic border.
Brush the crust with egg wash and sprinkle with coarse sugar.
1 large egg, 2 Tablespoons coarse granulated sugar
Drizzle the melted butter over the peach filling.
1/4 cup unsalted butter, melted
Bake in the oven for 30-35 minutes, or until the crust is golden and the peaches are bubbling.
Let cool for 10–15 minutes before slicing. Serve warm with ice cream or whipped cream.