Thaw the pastry as directed on the packet.
Peel, core and finely dice the apples.
Place the diced apples, brown sugar, cinnamon, nutmeg, slivered almonds and cornstarch into a bowl and mix until well combined.
Preheat the oven to 350°F / 180°C.
Lightly spray a mini muffin tray with spray oil.
Lay a sheet of puff pastry flat and cut into squares large enough to cover the holes of the mini muffin tray.
Line the muffin holes with the puff pastry pieces, pressing down into the cavity to make room for the filling. Repeat with all remaining pastry until 32 holes have been lined.
When all holes have been lined, fill each hole ¾ of the way with apple filling.
Bake in the oven for 15-20 minutes or until lightly golden brown.
Cool on a cooling rack. Lightly dust with powdered sugar if using.
Enjoy either warm or cold.