Preheat oven to 350°F. Place pastry shells on rimmed baking sheet. Using a pastry brush, lightly coat shells with melted butter.
Whisk Chobani, pumpkin, egg, brown sugar and pumpkin pie spice in a medium bowl until smooth.
Spoon about 1 T filling into each shell and bake until filling is set and shells are golden brown, 12-14 minutes. Remove from oven and cool completely before topping with whipped cream and a mint leaf.