Preheat the oven to 450˚.
Roll the pie crust out for a 9" pie pan and press into pan; set aside.
In a blender or food processor, blend the cottage cheese until creamy and smooth. Put it in a mixing bowl and add the flour, sugar, salt, and eggs. Mix until smooth. Add the milk and stir slowly.
Pour the custard into the pie shell and sprinkle with cinnamon. It has a good chance of boiling over so if you have one of those pie drip pans this is the time to use it!
Bake for 10 minutes, then reduce the heat to 300 and bake at least another hour. It will be jiggly in the middle, but will set as it cools.
Refrigerate 2-3 hours. Sprinkle with powdered sugar and serve.