In a medium bowl, whisk together the sugar, flour and
egg yolks. Bring milk, in a small saucepan, to the boil.
Whisk in egg yolk mixture, stirring all the while
until mixture thickens and begins to boil gently.
Remove from heat. Stir in butter and vanilla.
Cool and refrigerate until needed.
Cover with plastic wrap to avoid skin
from forming on top of custard.

Chocolate glaze:
2 oz. semi-sweet chocolate
1 tbs. butter
1-1/2 c. icing sugar
1/2 tsp. vanilla
1/4 very hot water

In a double boiler, melt the chocolate with the butter.
Add the icing sugar and vanilla and stir until smooth.
Add enough water to make a thin glaze.
Cool one minute, then drizzle over doughnuts
or dip doughnut top surfaces into glaze.
If glaze gets too stiff, add more hot water to make it workable again.