Pre-heat oven to 350 Degrees Fahrenheit.
In a mixer fitted with a paddle attachment, mix together the flour and cubed butter. Mix until it looks like a "cornmeal" consistency. You can also do the same thing in a food processor.
Once butter and flour is mixed well, add in a Tb of cold water and watch for the dough to "come together" more. We added 1 Tb and waited about 30 seconds, and then added a second Tb. In total, we added 3 Tb. You know its ready when you can grab a small amount of dough, squeeze it and it holds together.
Divide dough in half (this will make the top and bottom), wrap in plastic wrap and chill for 15 min.
When ready, roll out 1 dough ball gently on a VERY well floured surface. Roll in a circular motion, counter-clockwise. As cracks form at the edges, close them up and continue rolling. Roll from inside out and make sure dough is large than the baking dish you have.
Once ready, roll the dough over your rolling pin and onto your pie dish. Crimp the edges together and make sure if fits in there well, but don't stretch the dough again. Poke the bottom of the dough with a fork.
In a separate bowl, mix together the apples (rosewater if using), blueberries, flour and sugar. Set aside.
Meanwhile, work with the other dough that you're going to make the lattice with.
Do the same rolling as you did with the first dough ball.
Once rolled out, use a sharp knife or even a pizza cutter, and cut the dough in half and then in thick strips.
When the pre-baked pie shell is done, add in the fruit mixture. It will look like a lot, but don't worry, it cooks down.
To create the lattice, start with the largest/thickest piece and go from the middle-out, while inter-lacing.
So put 2 strips of dough vertically and then 1 strip horizontally, while the horizontal strip overlaps 1 vertical strip.
When you are done lacing the dough, crimp all the edges around securely. If you have any leftover dough, DON'T throw it away, crimp it to the sides.
Brush the top with egg wash and a healthy dusting of brown sugar.
Bake at 350 for 50-60min until crust is golden brown and fruit is bubbly.