Grandma Bevie's Butterscotch Pie

This is my husband's very favorite pie in the whole world!   The only problem is that Grandma Bevie makes the best butterscotch pie and honestly I don't think any attempt I make at making this pie for him will come close to being as good as hers.  This year we are not with his family for Thanksgiving which means that it is my turn to try to make this pie.   I have faced the fact that mine will never be as good as hers and I am ok with that!   So here is my attempt at it!

1 frozen pie shell that you bake ahead of making this filling (follow the instructions on the pie shell bag or box to bake it.)

2 cups of milk hot ( that means put 2 cups of milk in a sauce pan and heat it up but keep stirring because you don't want to scald the milk- just heat it up)  I would say use medium heat for this project!!

In a separate bowl combine:

1 cup of brown sugar (You may need to add a little more- I think I added 1/4 c more.)
1/2 cup sugar
a pinch of salt
and 3 beaten egg yolks

Mix that together!

When the milk is hot, add the sugars, salt and egg mixture in to the sauce pan and keep stirring...never quit stirring!

Then add to the sauce pan still stirring:
1/2 C of flour
1 tablespoon of butter or margerine
1 teaspoon of vanilla

Still over medium heat keep stirring the mixture until everything is mixed in very well and watch for it to thicken.   You can feel that it is thickening.  Take this off the unit and set aside to let cool for a few minutes.   Then you pour the filling in to the baked pie shell and let it cool and set up.  Refrigerate and enjoy with whipped cream on it.