Preheat oven to 350°F (175°C).
Mix flour, sugar, melted butter, and vanilla extract to form the crust. Press into a pie dish.
Bake the crust for 10 minutes. Remove and set aside.
In a saucepan, heat milk until warm. In a bowl, mix sugar, cornstarch, flour, and vanilla extract.
Slowly add the dry mixture to the warm milk, stirring constantly until thickened.
Remove from heat, add butter, and beaten eggs. Mix well.
Pour the filling into the baked crust. Sprinkle with ground cinnamon.
Bake for 20 minutes or until set. Let cool before serving.