Grease a large baking sheet.

Peel, core, and cut the apples into 1/4-inch slices. Place in a medium-sized bowl. Sprinkle with the lemon juice.

Cut the butter into small pieces; add to the apple slices.

Mix the sugar and cornstarch. Stir into the apple mixture

Divide the pastry into 8 equal parts and roll into 6 or 7-inch squares.

Spoon the filling onto the center of each square. Brush the edges with milk and fold over to make a triangle.

Press the edges together to seal and crimp with the tines of a fork. Using a sharp knife, make a steam vent in the middle of each. Place on the baking sheet and refrigerate for 15 minutes.

Meanwhile, preheat over to 425 F.

Brush the turnovers with milk and sprinkle with sugar. Bake for 30 minutes, or until golden brown. Remove from the baking sheet and serve warm or cold.