In a medium sauce pan, combine butter, sugar, water, cornstarch, cinnamon, nutmeg and salt together. Melt over medium heat and bring to a boil. Boil 2 minutes, stirring frequently, and then add in apple. Bring back to a boil over medium-high heat and cook for 5 minutes, stirring often. Remove from heat and let cool.
For the Crumb Topping:
Mix the brown sugar, cinnamon, and butter together and then mix in the flour until thick and crumbly. Set aside.
Preheat oven to 400 degrees F and line two baking sheets with parchment paper.
Unfold one thawed puff pastry sheet at a time and roll out to 10x10 inches. Use a pizza cutter and make 12 even strips. Connect two strips together by overlapping by a half inch and pressing together. Twist the ribbon and then snail it around itself and press the end to the rest of the dough. Place on a parchment lined pan (6 danishes per baking sheeand press the middle down. Place a spoonful of apple filling in the wells.
Mix the egg and water together in a small dish and brush the pastry with it. Sprinkle the crumb topping over the tops of each danish and then bake for 16-18 minutes until edges are golden. Let cool for 5 minutes and then glaze.
For the Glaze:
Mix glaze ingredients together and drizzle over the warm apple danish.