Heat a saucepan over medium-low heat and add the butter. Toss in the apples with the sugar, apple pie spice and salt and toss. Cook, stirring often, for about 5 to 6 minutes until the apples start to soften.
Preheat the oven to 425 degrees F.
Place a sheet of parchment paper on your work surface. Place one sheet of puff pastry on top. Spoon 1 to 2 teaspoons of the apple cubes on the puff pastry – sort of like you’re working on a tic tac toe board. Place a slice or a few crumbly pieces of cheddar under and on top of the apples. Cover the entire thing with the other sheet of puff pastry. Use a large knife or pizza cutter to cut the pastry into 9 squares, just around the edges. Use a fork to press the edges together.
Brush the tops with the beaten egg wash. Sprinkle with the raw sugar and a touch of Apple Pie Spice. Bake for 20 to 25 minutes, or until golden brown. Let cool slightly, then serve. These are best served shortly after making.