Preheat oven to 180 degrees Celsius.
Blitz the butter, flour and sugar ingredients together in a food processor until it until it has the consistency of breadcrumbs. Add the egg and blitz until it all clumps together to form a dough.
Press into a lightly greased 26 cm tart dish. (This dough does not need to be rolled out). Chill in the fridge while preparing the filling.
Heat the milk together with the cinnamon sticks in a medium sized pot (do not boil).
In a mixing bowl whisk together the egg yolks, sugar, flours and salt until creamy and light. The mixture will be quite thick. Once the milk is hot, whisk two ladles full of the milk into the egg mixture to temper the eggs.
Pour the egg mixture back into the saucepan and cook until thickened, whisking continuously. Cook the custard for 2-3 minutes until thick and smooth.
Remove from the heat and whisk in the butter and vanilla.
Whisk the egg whites in a clean glass bowl until soft peaks form and fold into the custard.
Pour into the chilled pastry case and sprinkle with ground cinnamon.
Bake for +- 30-35 minutes.