Ingredients
1/2 c. sugar
3 tbsp. cornstarch
2 c. evaporated milk
3 egg yolks, slightly beaten
1 tsp. vanilla
Directions
In sauce pan, whisk together sugar and cornstarch. Gradually whisk in milk until smooth. Add slightly beaten egg yolks. Turn heat on to medium - low and stir constantly. Boil 1 minute. Remove. Stir in vanilla. Cover surface with plastic wrap and refrigerate until cool.
To fill doughnuts: Place custard in a pastry bag with a large tip. Poke tip into doughnut and squeeze in the custard.
from: http://mybiscuitsareburning.blogspot.com/2011/09/custard-filling.html
Adapted from Cooks.com