To make the crust:
Preheat oven to 350 degrees Fahrenheit. Lightly grease your baking dish (8-inch square baking glass is preferred).
In a food processor or blender combine the flour, sugar, salt and cinnamon (optional). Pulse briefly until combined. Add butter and pulse until moist crumbles are made. Make sure it is wet, there should be dry. Press the dough into the bottom of the baking pan, and side about 1 inch. If you are using a square pan, turn the dough on a well floured sheet of parchment. Form a square with the dough. No transfer of an inch pan and press the sides.
Place the tray in the freezer for about 20 minutes. Bake the crust in the oven for about 20 minutes until golden. Remove and let cool completely cortex. Reduce oven to 325 degrees
To make the filling:
Mix sugar, flour, salt and zest. Add eggs, lemon juice and cream. Whisk until blended and creamy. Carefully pour over dough baked (cooled). Bake for 20 minutes until the filling is, but still shakes slightly when shaken baking dish. Let cool for about 30 minutes. Run a knife around the inside of the dish to remove dandruff then cool completely.
Cut into small rectangles or squares and remove from the plate with a spatula. Sift powdered sugar over the bars to serve.
