Preheat oven to 350 degrees and lightly butter the tart pan.  

Graham Cracker Crust:   In a food processor, pulse the crackers until they are crumbs. Add the sugar and cinnamon and pulse to combine. Slowly drizzle in the butter as you pulse the mixture.

Add the Graham cracker mixture to the tart pan. Using a measuring cup, spread it out evenly and press against the edge to create that sharp, clean edge.

Bake it for 8 minutes. Then set it aside and start the filling.  

Lemon Filling:    Zest two lemons and set aside in a mixing bowl. In a separate mixing bowl, combine the sugar and flour to break up any lumps. Add the eggs in one at a time while mixing and then the lemon juice. Mix well to combine.

Pour through a sieve into the mixing bowl with the lemon zest.  With a spatula, mix well to combine the lemon zest throughout the filling. Pour filling into the tart dish and bake for another 22-25 minutes.  

Note: Pouring the filling through a sieve ensures a consistently smooth texture and is a personal preference.

When the baking time is up, remove it from the oven and allow it to cool at room temperature. It will set as it cools. Once at room temperature, place it in the refrigerator overnight.

Dust with powdered sugar just before serving.  

Optional: serve with fresh berries and whipped cream