In a large bowl combine the flour, cinnamon and cubed butter. Make sure to toss the butter and flour so the butter pieces are covered with flour.
With your hands use your thumb and forefingers to work the butter into the flour. You want to do this over and over again until your butter is all pea sized pieces. A few larger pieces are ok!
You want to work quickly because keeping the butter cold is very important for a flaky crust!
The mixture at this point should resemble a course meal.
Add the ice water in a tablespoon at at time and use your hands to toss together.
Keep adding water a tablespoon at at time and mixing together until the dough starts to come together.
Do not add too much water as you do not want the dough to be sticky.
Do not work the dough too much! You can knead it a few times on a floured surface to get it to come together but a few dry pieces of flour and cracks in the dough are ok!
Cut the dough into 2 pieces and flatten the discs. Wrap in plastic wrap and chill in the fridge for 1 hour before use.