I made ice cream once before (apple crumble flavour) and I made it with a custard base. I had the impression that good ice cream was made with a custard base, but none of the Ben & Jerry's recipes follow this. A quick look in Leiths revealed there were three methods: custard base, mousse base, and all in one. The Ben & Jerry's recipes seem to mostly all in one, but there are a few mousse ones too. I decided to see how a custard base stood up to an all in one base, and whether there would be any difference in taste.
Before starting, the only difference between the recipes seemed to be that B&J used whole eggs, whereas Leiths only used the yolks. Leiths didn't have a custard-based vanilla recipe, so I went for a hybrid version of a coffee ice-cream and creme-anglais recipe. B&J also wanted me to use extract, but I wanted to use vanilla beans, so I adapted that recipe a bit too.
Ben & Jerry's
I made this using the Sweet Cream Base that appears frequently throughout the book. I infused the double cream with a split vanilla pod, and used vanilla sugar instead of plain. After whipping the eggs and the sugar, I added whole milk and the cream. The mixture was very runny, and produced a much larger amount than I expected. I put half in the freezer and half in the fridge to use as a base for another flavour.
When I went back 30 minutes later to whisk out any ice crystals, it had already frozen quite well. I was a little worried when the lumps didn't seem to whisk out as easily as I'd hoped, but when I tasted one, it was smooth, not icy.
I began by infusing scalded milk with a vanilla pod, and then whisked an egg yolk with a small amount of vanilla sugar. Once the milk had infused, I added in the egg mixture and stirred for a full 25 minutes before the custard thickened. I actually managed to get twinges in my tendons from the intense stirring!
Then I mixed in a little double cream to loosen the custard, and froze it. Again it was quite lumpy after the first couple of whiskings, but when I tasted the lumps they were obviously icy unlike the B&J mixture. After a few whiskings, it was less icy.
As you can see from the picture, the ice cream looked very similar, although the custard based one was frozen harder than the Ben & Jerry, which was almost soft scoop.
I prefer a firmer ice cream, so I was instantly more excited about trying the custard base. Tasting the mixes before and during the freezing process, I had preferred the custard base as it was richer and creamier.
However, when faced with a whole scoop rather than a teaspoon-full, the Ben and Jerry mix won over. The custard base was too rich to eat lots of, and had a slightly unpleasantly "eggy" taste that didn't seem right. Also, the vanilla flavour was very intense, almost chemical. The Ben & Jerry's was still rich, but the vanilla taste was more subtle. Both had small ice crystals, but I suspect this was due to me going out for a few hours instead of staying home and churning them as I should have!
I suspect that either of these ice creams would go well with a dessert, but the B&J is more suitable for eating on its own than the custard one. I think it would be very difficult to tell the difference between the two methods if you tasted the ice creams separately. It was only tasting them back to back that the differences became clear.
The left-over B&J base is going to become rhubarb and custard flavour over the weekend, and now that I am sure that I can produce a decent all-in-one ice cream without a churning machine, I can't wait to try some of the other recipes in the book!
EDIT: Custard base went very well with the Breadwinner Banana Tatins.