(adapted from The Martha Stewart Living Cookbook, 2000)
Makes about 1 quart
2 cups shelled hazelnuts (8 ounces)
3 cups milk
5 large egg yolks
2/3 cup sugar
1 cup heavy cream
1 T. hazelnut liqueur, optional
Preheat oven to 350° F. Toast nuts in a single even layer on baking sheet until the skins are split, about 8-10 minutes. [don’t wait until you can smell them a lot, they’ll be burned about 3 seconds later.] Rub the warm nuts with a clean kitchen towel to remove the brown skins. [this is fairly laborious but you’ll remember how worth it all the work was when you take your first bite.] Return to pan; toast until fragrant and golden brown, about one minute more. Let cool completely, grind coarsely [in food processor] or chop finely [with a knife].
In a medium sauce pan, heat milk and chopped nuts. Bring to a gentle boil, cover, and remove from heat. Let steep at room temperature for 2 hours. Pass through a cheesecloth-lined strainer, pressing hard on solids and reserve milk. Discard solids [or if you can’t bear to, they can be used for a few ingenious things—call me, I’ll fill you in].
Combine egg yolks and sugar in the bowl of an electric mixer fitted with the whisk attachment. Beat at medium-high speed until very thick and pale yellow, about five minutes. Meanwhile, return milk to a simmer.
Prepare an ice-water bath. Whisking constantly, add half the milk to the egg yolk mixture to temper it. Stir egg mixture into milk in sauce pan and cook over low heat, stirring constantly with a wooden spoon, until mixture is thick enough to coat the back of a spoon. [this can be a tricky thing to do—lots of good cookbooks will describe better what kinds of tests you can do to determine the doneness of a custard if the spoon test is not clear to you].
Remove from heat and immediately stir in cream and hazelnut liqueur, if using [I have tried the hazelnut syrup made for using in lattes—it’s pretty good but not strictly necessary]. Pass mixture through a fine sieve [to remove any possible scrambled egg bits] into a medium bowl set over the ice bath to chill. Freeze in an ice-cream maker according to manufacturer’s instructions [or follow David’s great instructions for liquid nitrogen ice cream]. Freeze in a plastic container up to one week [if it lasts that long].
Pistachio variation: cover and bring a sauce pan of water to boil. Add pistachios and cook 30 seconds. Remove from heat and drain. When cool enough to handle, remove outer skins and discard. Toast in 350° F oven until aromatic, about 5 minutes.