Preheat oven to 325 degrees.
Beat egg yolks, pour in sugar and flour and beat until creamed together.
Pour in melted butter (be sure the butter is cooled slightly to prevent the eggs from cooking) and beat until creamy.
Add remaining ingredients and beat until combined.
Whip egg whites in a separate bowl. Fold into custard mixture.
Pour into pie shell. Set on baking sheet. Bake in middle of preheated oven for 1 hour to 1 hour 15 minutes or until done in the center. A toothpick should come out clean even if the center still jiggles a little.
Allow to cool completely or even chill overnight in the fridge before serving.
And if the center cracks, well, just decorate it with pretty pastry shell leaves. ;)