Here are some general instructions that you can use to turn any raw egg recipe into a cooked custard-based recipe. There are other methods, this is just the one that I have used. I'd rather not take the chance of curdling the cream, so I add it after the heating of the other ingredients. The most important point is that you never want to boil or curdle the eggs or you will have scrambled egg ice cream.
Custard base ice cream
1. Using the same ingredients from the specific recipe, beat the eggs in a small bowl.
2. Combine the milk and sugar in a saucepan or double boiler. Heat until simmering. Since the mixture will condense with cooking, you might consider adding an additional 1/4 cup or so of milk.
3. Remove from heat and slowly pour the hot liquid into the beaten eggs while whisking constantly. Pour the egg mixture back into the saucepan. Heat over medium heat, stirring constantly until mixture just begins to bubble and is thickened. The mixture should coat the back of a spoon and a line drawn by your fingertip through the custard on the back of the spoon should remain visible. Do not boil.
4. Remove from heat and allow to cool, stirring occasionally to prevent a skin from forming. Unless you are very confident that you have no lumps or cooked egg particles, it is a good idea to strain the mix before cooling.
5. If you are making chocolate ice cream, add the chocolate after the mixture has thickened but while it is still hot. Stir well until the chocolate is melted and is well combined. Cool the mixture.
6. You can speed the cooling process by putting the pan in an ice bath for 15-20 minutes first (photo above). Put the pan in a larger bowl filled with ice and a small amount of water. Don't forget to stir until the mixture is cool enough to not form a skin.
7. Add the cream, flavoring, any fruit purée, and any other ingredients when the mixture is cool. This mix will probably need 2-3 hours chilling time in the freezer before freezing in your ice cream maker.
Note: If you are making a fruit ice cream where the quantity of fruit may not be exact, you can reserve about 1/2 cup of milk. Check the amount of your mix after all the ingredients have been added. You may or may not need to add this remaining milk to the mix. On the other hand, this recipe may lose some volume through cooking. Check your final measurement and add additional milk at the end, if necessary. (This is assuming that you want to make the maximum amount of ice cream without risking an ice cream volcano erupting from your machine.)
See also my ice cream making tips (especially for the tropics) and, if you are in the market for a machine, my ice cream maker reviews. Click the 'LG Recipes' topic in the sidebar for additional ice cream recipes.