Amish Caramel Cake (pie)

3 cups brown sugar
3 cups water
2 tablespoons butter
1 cup flour
3 cups milk
6 egg yolks
Boil brown sugar, water and butter together for 2 or 3 minutes for a good strong caramel flavor. Slowly stir flour mixture into boiling syrup, stirring constantly until it comes to a boil.
Remove from fire; cool 5 minutes and stir once.
Pour into 2 baked pie shells.
Top with either a meringue from the egg whites or allow pie to cool and top with whipped cream.