Among the many virtues of the movie Julie & Julia is the reverence paid to great cookbooks in a cook’s life and development. Great chefs share their best work and we get to enjoy the benefits. Last weekend, my guide was the wonderful French chef Daniel Boulud with his gratin forestier – a potato gratin cooked with mushrooms. I have long been a fan of potato gratins, particularly the gratin dauphinois variety that is simply good sliced russets cooked in cream with, typically, gruyere cheese. These gratins fill the kitchen with rich, warm aromas, whetting the appetite with the foretaste of a well-filled belly and a satisfied palette.
Boulud’s version, though, is a wonder – he layers thinly-sliced potatoes with a layer of wild mushrooms, drenched in cream and baked until soft, custardy and saturated with cream. I used three varieties of mushrooms – dried Italian porcini and shittakes and fresh baby portobellos. After reconstituting, the porcini and shittake are cooked separately in butter with a little salt and pepper. Likewise the portobellos. All three are then tossed with finely-chopped garlic and fresh thyme.
With a mandolin, slicing the potatoes is easy. After preparation, they are soaked in cream with salt, pepper and nutmeg. After that, it’s a simple matter of layering the potatoes with the cream and potatoes, coating the top with a thin layer of grated parmigiano, and baking slowly until cooked and light brown.
The guests loved it and so will you. Many thanks to Daniel Boulud.