Problem my be in the methodWhen I make custard, creme anglaise, or ice cream I follow the same basic method. All three are very similar considering that the ingredients are eggs, sugar, and milk or cream.
1. Bring the cream to a boil in a pot.
2. In a mixing bowl, whish together the yolks and sugar. (Make sure to mix them well, or the sugar will dry out the yolks)
3. Slowly pour the cream into the mixing bowl and whisk until the egg and sugar mixture is incorporated.
4. Return the cream, eggs, and sugar to the pot and cook to nappe*.
5. Once the mixture has reached Nappe, pour it into a clean mixing bowl over an ice bath and stir lightly until cooled.
6. Once cool, the custard micture is ready to use (Bake).
*Nappe is a measure of sauce thickness. It is determined by stirring the sauce with a wooden spoon and then running a finger across the back of the spoon. If the sauce down, the sauce is not yet to nappe, if the sauce holds it's place it is at nappe.
If this method does not work, the ingredients can also be cooked over a bain marie, or double boiler. the double boiler method takes a much longer time, but it is easier to control due to the low heat involved.
1. Whisk together eggs and sugar, then add the cream.
2. Bring water in the bottom section of the double boiler to a boil, and add eggs, cream and sugar to the top section. Make sure that the water does not touch the top section.
3. Cook to nappe, stirring the entire time to prevent the eggs from coagulating.
4. When the mixture reaches nappe, cool it in a bowl over an ice bath.
The ice bath is a vital step in these processes because it stops the eggs from overcooking. Overcooking your eggs will always result in curdling the custard.
Also, try placing the custard pan in a waterbath (a larger pan filled with hot water.) This insulates the pan and assures that the eggs reach the proper temperature slowly, preventing curdling. The water should reach about one-half to three-quarters of the way up the smaller pan.
Hope this helps,