2. Spread the chopped almonds and walnuts out on one of the baking sheets and toast the nuts in the oven. They will need 10 minutes or less to turn golden brown, so keep a close eye on them and stir them at least twice. When the nuts are toasted, remove them — with the liner — from the baking sheet and cool the sheet. Transfer the nuts to a plate, then reline the sheet and use it to bake the cookies.
3. Put all the ingredients, including the nuts, in a medium heavy-bottomed saucepan. Set it over medium heat and stir constantly with a silicone or wooden spatula until the ingredients are just warm to the touch. Remove from the heat.
4. Drop the batter by slightly rounded teaspoonfuls onto the baking sheets, leaving about an inch of space between the mounds.
5. Bake the cookies for about 20 minutes, rotating the pans from top to bottom and front to back at the midway point. When properly baked, the cookies will be puffed, cratered, shiny and dry. Remove the cookies from the oven and let them remain on the sheets for 5 minutes before gently prying them from the liners and transferring them to racks to cool to room temperature.
Storing: Kept in a cool, dry place at room temperature (they should never be refrigerated), the cookies will hold up for about 3 days. As with all meringues, humidity will make them go soggy and sticky.
Andrea Reusing is the creator of the restaurant Lantern in Chapel Hill, N.C., and author of the book Cooking in the Moment: A Year of Seasonal Recipes. In this installment of The Key 3, she shares with Lynne Rossetto Kasper the techniques behind three of her favorite recipes: Turnip Soup, Overnight Braised Short Ribs and Tomato Salad.