Note: See blog post for photos to demonstrate the step-by-step process.
Preheat oven to 400°F.
Remove puff pastry from freezer and let it start to thaw as you make the apple filling.
In a pot over medium heat melt butter. Add chopped apples and cook, stirring often for 5 minutes. Add the brown sugar, and cinnamon and salt. Stir to combine and cook for 3 minutes or until apples have softened slightly and mixture has thickened. Remove from heat and let cool.
Add the egg and water to a small bowl (for the egg wash), using a fork or whisk beat the egg until smooth.
On floured surface roll out puff pastry to a 12 inch square. Cut into 4 equal sized squares. Repeat with other puff pastry sheet.
Spoon cooled apple mixture over half of each square, leaving a half inch border. Brush a small amount of egg wash around the border. Fold the puff pastry half over to create a triangle. Use a fork tines to seal the edges. Place each turnover on a parchment lined baking sheet. (I could only fit 4 turnovers on my baking sheet.)
Brush tops with egg wash. Create 2 -3 small slits on top of each turn over. Sprinkle with sugar or turbinado sugar. Bake for 18-22 mins or until golden and puffed up.
Whisk the glaze ingredients in a medium sized bowl. Drizzle over top warm turnovers.