- Make sure that you cook through the pie filling for a decent amount of time so that the cornflour has cooked, or else it will taste of glue.
- Make sure that you add a sufficient amount of cornflour so that the filling doesn't seep through the base... but don't go overboard (you can add extra cornflour a heaped tablespoon at a time so that you don't make an error one way or the other)
- Make sure you sieve the cornflour in so that it doesn't get too gluggy.
To make this I essentially followed the same method as the one I use for making my Cheats Cherry Pie, but used frozen blueberries. There's no need to add any liquid as the juice released from the blueberries as they cook will provide enough fluid to work with for the filling. As well as cinammon, I also fine-grated in the rind of a lemon.