Blueberry Custard Pie

I am forever trying to make good, healthy food apprear out of empty cupboards and fridges. Sometimes amazing this occur. Sometimes the seed of something amazing occurs. That was tonight. The pie didn't turn out quite right but it gave me the idea for how to make it amazing.
I made a basic shortbread crust and pre-baked it.
Then I made a butter/flour roux and added 3 cups of water to it. Next time I think I need to use less water. And maybe even milk would be better. After it thickened into custard consistency, I added 1/2 cup of sugar. I think I should have added some vanilla here too. Then I added to the custard some mostly thawed blueberries, about 2 cups. I let this warm together off the heat and then added it into the crust. I baked this at 350 for 30 minutes and then let it cool for another 30 off the stovetop. I think it would have thickened better with the cup less of water. It was still good! But next time it will be even better.