Most creme brulees require baking, however after a little research I did find a recipe in "On Cooking" (Sarah Labensky/Michael Hause) that came from Chef Vincent Guerithault of Vincent on Camelback in Phoenix, AZ and his was similar in that it was not baked.
First, just making creme anglaise with heavy cream isn't going to do anything to let it set up into a firm custard. More egg yolks or starch would be needed.
Supposing that this really does work and it was something you perhaps did, my guess would be that it was either mixed too much (breaking down the proteins trying to link together) or too vigorously (incorporating air which weakened the protein links). In your description you say you "beat it". Did you beat it or stir it? It should be stirred back and forth zig-zagging across the bottom of the pan with a wooden spoon or heat-safe rubber spatula to keep from whipping air into it.
Time, temperature, and eggs/dairy ratio are going to be the main issues in getting custards to set.
Egg proteins begin to set at 160 degrees but curdle at 180 so there's very little "wiggle" room temperature wise.
According to Shirley Corriher's "Cookwise": 2 egg yolks will just barely thicken 1 cup of milk or cream. Her Creme Anglaise recipe uses 5 egg yolks to 1 cup of milk and 1/2 cup heavy cream which is more yolks and less liquid than Julia's and this isn't intended to set up. 1 teaspoon of starch isn't going to provide the thickening power that is needed, it's there to keep the yolks from curdling as easily.
The recipe I use and many others I've referenced (including Chef Vincent's), use a ratio of about 6-7 yolks per cup of cream.
Also, if using a starch, you need to nearly bring the custard mixture to a boil (as is common in puddings and cream pie fillings) otherwise an enzyme in egg yolks known as alpha-amylase will eat away at the starch bonds and break them down into a watery mess.
Chef Vincent's does not use any starch.
If you want to use that recipe, I would increase it to 10 egg yolks. After the hot cream is tempered into the egg yolks then return to the heat and cook, stirring constantly, until very thick but do not let it boil. Remove it from the heat and strain into a clean metal bowl and chill over an ice bath to cool quickly. Once cool, spoon into your desired serving dish or a cookie cup and caramelize the top with sugar.
I think it all got too hot, but there might be other problems.
- Did you mix the cornstarch in completely? Leaving undissolved cornstarch is a sure way to obtain 'blobs'.
- Did you pour the hot milk onto the egg-mixture? You should do that very slowly and whisk vigorously (while trying to splash everything). If the eggs get too hot, they will coagulate.
- Did you use a double boiler? Putting the pan on an open flame will make the bottom too hot and the eggs will coagulate.
- Even if you did use a double boiler, did you whisk regularly while heating? The eggs at the bottom will become far warmer than the eggs in the center...
As rumtscho mentioned, a thermometer will be useful for monitoring the done-ness of the custard.
Generally, a fully cooked custard should not exceed 80 °C; it begins setting at 70 °C.
Source: Wikipedia
Best Answer
A custard royale is not stirred during cooking, this leads exactly to the scrambeled eggg effect you had. This is fundamentally different from the standard custard process you are probably familiar with.
The (preheated) cream is mixed with the egg and/or yolks, then put in the vessel it's supposed to be cooked in.
It can be cooked over barely simmering water or in the oven in a bain marie at 90C. You simply give it enough time to solidify, which may be somewhere between half an hour to almost an hour, depending on the thickness. Cooking in an oven tends to take a bit longer than on stovetop.
Let cool completely before unmolding and cutting.