1 cup/250 ml sugar; 3 tblsp/45 ml cornstarch (called corn flour in Ireland); 1/4 cup/50 ml flour; 1/8 tsp/0.5 ml salt; 1/3 cup/75 ml cold water; 3 egg yolks; 2 cups/500 ml boiling water; 2 tblsp/30 ml butter; 1 tsp vanilla extract.
In a mixing bowl, mix together dry ingredients.
In the top of a double boiler, beat cold water and egg yolks together, before adding dry ingredients.
Stir until smooth, then add the boiling water.
Cook on med-high (not too high or it will burn) heat, stirring constantly, until smooth - about 15 minutes.
Whisk in butter and vanilla extract; remove from heat.
This custard can be divided into portions and frozen. Even though I exclusively make it for New Year's, it is a lovely dessert year-round!
Also, I originally adapted this recipe from a lemon meringue pie recipe, so if you want to make lemon meringue pie, add 1/2 cup/125 ml lemon juice and grated zest from one lemon when you are whisking in the butter. Cool the lemon custard and add to a pie shell. Use the egg whites to make a meringue: beat 3 egg whites with a pinch of salt and slowly add 6 tblsp/90 ml sugar, beating until stiff. Top the pie with the meringue before baking for about 10 minutes at 375F/190C or until meringue is lightly browned.
I have also previously adapted this recipe to make a coconut cream pie! As with the lemon meringue pie, add about 1/2 cup/125 ml dessicated coconut to custard when whisking in the butter. Add the coconut custard to a pie shell and top with meringue made from the egg whites and bake as above.