Guide
Custard or Philadelphia: choosing a base
Nearly every ice cream starts as milk, cream and sugar. The only real decision is whether to add egg yolks and cook it. Here is what each choice does to the result.
The short answer
Use a custard base for rich, smooth flavours that keep well: vanilla, coffee, caramel, chocolate, nuts. Use a Philadelphia base, which needs no eggs and no cooking, when you want the flavour to taste fresh and clean: fruit, mint, herbs. If you are not sure, custard is the more forgiving of the two in the freezer.
The custard base (French style)
Egg yolks are whisked with sugar, warmed with the milk and cream, and cooked gently until the mixture thickens. The yolks bring fat and lecithin, which is a natural emulsifier: it holds fat and water together and keeps ice crystals small.
That is why a custard base stays smooth for a week or more in the freezer, while other bases start to feel coarse after a few days. It also tastes richer and rounder, and has a faint eggy sweetness that suits toasted, roasted, dark flavours.
- Best for: vanilla, coffee, chocolate, caramel, nuts, anything browned.
- Costs you: twenty minutes at the stove and a little nerve.
- Keeps: a good week or two before the texture drops off.
The full method is written out in the vanilla bean custard base recipe.
The Philadelphia base (no eggs)
Stir sugar into milk until it dissolves, add cream and flavouring, chill and churn. No eggs, no cooking, nothing to curdle. It is named after the American city where the style was popular in the nineteenth century.
Without yolks in the way, the flavour arrives cleaner and brighter. Strawberry tastes of strawberry rather than of strawberry custard. The trade-off is texture: less fat and no emulsifier means it firms up harder and turns coarse sooner.
- Best for: fruit, mint and herbs, anything delicate.
- Costs you: nothing. It is about ten minutes’ work.
- Keeps: three or four days at its best.
Roasted strawberry and blueberry ripple both use this base.
Side by side
- Flavour: custard is rounder and richer; Philadelphia is cleaner and more direct.
- Colour: custard is cream to pale yellow, which can muddy pale fruit; Philadelphia stays white.
- Texture straight from the freezer: custard stays scoopable for longer; Philadelphia sets firmer.
- Effort: custard needs a stove, a thermometer if you are cautious, and a sieve. Philadelphia needs a whisk.
- Risk: custard can scramble. Philadelphia has nothing to go wrong.
The other bases worth knowing
- No-churn: whipped cream folded into condensed milk. Not really either family, but the easiest route to a frozen pudding.
- Gelato: more milk, less cream, sometimes a few yolks, churned slower and served warmer. Denser and more intensely flavoured.
- Sorbet: fruit, sugar and water, no dairy. Sugar alone controls the texture.
- Frozen yoghurt: thick, full-fat yoghurt sweetened and churned. Tangy, and best eaten within days.
- Dairy-free: full-fat coconut milk or cashew cream, which have enough fat to behave like dairy.
So which should you make?
Ask what you want to taste. If the answer is the flavour of the dairy itself (vanilla, caramel, coffee, chocolate), the custard base flatters it. If the answer is fruit or a fresh herb, the eggs will get in the way.
Then ask when you are eating it. Ice cream for tonight can be any base you like. Ice cream to keep in the freezer for a fortnight should be a custard, because it will still be pleasant to eat at the end of it.
Everything else (sugar levels, fat, mix-ins) works the same way whichever base you pick.
Put it into practice