Mary Berry’s Very Un-French Secret To The Best Potato Dauphinoise

Mary Berry recently celebrated her 90th birthday with royal shout-outs and, per the baking legend, “cake and champagne”.

I celebrated it, too, by making some of her very best recipes. 

The Cordon Bleu-trained chef isn’t afraid of mixing up a classic; she puts cream in her bolognese (which was surprisingly good), makes a “Mexican lasagne” with tortilla wraps, and even whacks Thai curry paste in her tomato soup.

Every time I’ve given her twists a go, I’ve been pleasantly surprised. So, I withheld judgment when I read that her potato dauphinoise recipe involved a very un-French ingredient. 

Mary puts sweet potato in the dish 

The recipe, shared in Mary Berry’s Family Sunday Lunches, involves sweet potato as well as the more traditional King Edwards. 

The “floury” King Edwards become fluffy as they cook; sweet potatoes turn a little more mushy and, well, sweet as they bake. 

The chef slices both types of spud to the same thickness (or, should I say, thinness; she likes them very finely-cut) with a sharp knife or food processor. A mandolin would do, too. 

She layers a mixture of both spuds into a buttered dish with cream, stock, salt, and pepper. 

When all the liquid ingredients and potatoes have been used up, she presses down on the mixture for a compressed dauphinoise, then covers the lot in Parmesan cheese. 

She bakes the dauphinoise covered in foil for the first 40 minutes, then removes the cover and cooks it open-topped for a further 25-30 minutes until golden brown. 

Whether or not you agree with the sweet addition, King Edwards seems to be the way to go

Personally, I can see the appeal of sweet potato; it makes the dish more colourful, sweeter, and more texturally interesting.

Gordon Ramsay seems to use it in his version of the dish. 

But if you’re more of a fan of the traditional version, it seems other pros agree that King Edward or another floury spud like Maris Piper is the way to go. 

Nigella Lawson uses King Edwards; she also boils the potato in mash before adding it to the pan for a “lazy” step-skipper.