Grandma's butterscotch was my brother's favorite pie when we went down to the country to visit. My favorite was chocolate, so she usually made both and had them sitting on the table waiting for us. I miss those days,
1Place oven rack in middle position; preheat oven to 350 degrees F.
2In the top of double boiler, combine brown sugar, flour and salt.
3Add milk and stir until any lumps are dissolved.
4Cook over boiling water (do not let top pan touch the water) on medium-high heat, stirring constantly, for 10 minutes or until very thick.
5Remove from heat and add several spoonfuls of the hot mixture to the beaten eggs (about 1/2- 3/4 cup) and mix until smooth (this is called tempering the eggs; don't skip this step or you will end up with scrambled eggs in the filling!)
6Add egg mixture to the pan and, stirring constantly, cook over boiling water until thickened (approximately 2-3 minutes.)
7Remove from heat and stir in the butter and vanilla until thoroughly combined.
8Let cool slightly for a few minutes, then pour into pie crust.
9Make the meringue by beating egg whites until frothy.
10Add cream of tartar and beat until stiff, but peaks still bend.
11Gradually add sugar while beating; add vanilla and beat until combined and has stiff peaks.
12Spread meringue over filling, making decorative swoops and swirls.
13Bake at 350 degrees F for 15 minutes; remove and let cool and set up for at least 3 hours at room temperature or 1 hour at room temperature and 1 hour in refrigerator. Refrigerate leftovers.