Gluten free Blueberry pie

I love pie. Always have.  It's prime Blueberry season. I have already picked a few flats, and look forward to picking more.

METHOD
Prepare gluten free pie crust using this recipe from Gluten free on a shoestring, just omit the sugar.  Mix together with your hands, rubbing and breaking the butter until it's in small pieces:

2.25 gluten free flour (I used a mixture of one part tapioca starch to two parts brown rice flour)
1 tsp xanthan gum or psyllium husk powder
1/2 tsp baking powder
1/2 tsp kosher salt
10 TB butter, cold

Now add and mix until combined: 1/2 C to 3/4 C iced water

Chill for 30 minutes or more in the fridge. Roll out using two sheets of wax paper, form it in pie pan. Chill it again.

FILLING
Mix these together and pour into chilled prepared pie crust:
4.5 - 5 C washed blueberries (approximately 2 pints)
1/4 C gluten free flour
<=1/4 C sugar
dash of vanilla extract 
dash of lemon juice 

TOPPING
Prep the crumb topping but blitzing in food processor, until chunky:
1/4 C sugar
1/2 C gluten free flour (rice flours are nice and crispy texture)
1/3 C butter

Sprinkle over the top of the pie. Bake at 375 F for around 40 minutes, or until done/browned on top and bubbling.

ALTERNATE METHOD:
Blueberries make a great hand pie or turnover.  I used the pie crust and stuck a few blueberries (nothing else) and then closed up the pie dough. Cooked it for 15 minutes (?) until browned. Yum.