You can basically pour 1/2 of the mixture into 2 regular pie shells and the batter will not overflow during baking. However, if you try to put the entire mixture into a single deep dish pie shell, it will likely overflow. I always line a cookie sheet with aluminum foil to catch potential overflow. I also recommend cooking the pie(s) on a rack about 1/3 up from the bottom of the oven to prevent over-browning on top and ensure a more even consistency.

2 - 9" unbaked pie shells or 1 deep dish pie shell
1/2 cup butter - softened
2 cups sugar
3 rounded Tablespoons flour
3 eggs beaten
1 cup Buttermilk
1 tsp. vanilla

2 - 9" unbaked pie shells or 1 deep dish pie shell 1/2 cup butter - softened 2 cup s sugar 3 rounded Tablespoons flour 3 eggs beaten 1 cup Buttermilk 1 tsp vanilla

Have butter soft, add sugar - cream well. Add flour & eggs beat well. Stir in Buttermilk and vanilla. Pour into unbaked pie shell. Bake 350*
50 minutes + until knife inserted in middle comes out clean.