Preheat oil in deep fryer to 375F (use a thermometer if you're using a fry daddy!).
1−1/2 cups sugar
3 Tblsp. melted shortening
3 large eggs
1 cup milk
1 tsp. vanilla extract
5 tsp. baking powder
1 tsp. salt
2 tsp. nutmeg
2 cups mashed potatoes, cooled
3 to 3−1/2 cups flour

Beat eggs; add sugar, shortening and vanilla.
Add mashed potatoes and milk and beat with electric mixer until smooth.
Add flour, baking powder, salt and nutmeg.
Stir in additional flour to reach batter consistency (this is "by look and feel"−− It should still be somewhat will pick up more flour when you roll out the dough on a floured surface).
Chill the dough for several hours or overnight.
Take a portion of the dough and rough out to about 3/8 to 1/2 inch thickness, using flour as needed to prevent your rolling pin picking up dough.
Use a donut cutter and cut out your donuts.
Fry 3−4 donuts at a time −− turning when they are a nice golden brown.
Drain on brown paper bags to remove excess grease.