(From Nigella Lawson, "How to Be a Domestic Goddess: Baking and the Art of Comfort Cooking," Hyperion, 2001.)
For the macaroons:
5/8 cup or 3 ounces pistachios
3/4 cup confectioners' sugar
2 large egg whites
1 tablespoon sugar
For the buttercream:
1/4 cup or 2 ounces pistachios
1 2/3 cup confectioners' sugar
1/2 cup unsalted butter, softened
Preheat oven to 350 degrees. Line two baking sheets with parchment or wax paper.
Make the macaroons:
Grind the pistachios in a food processor with confectioners' sugar until as fine as dust. Whisk the egg whites until fairly stiff, but not dry. Sprinkle with sugar and whisk until very stiff. Fold the whites into the pistachio-sugar dust and combine gently. Pipe small rounds (2 to 3 inches in diameter) onto your baking sheet using a plain 1/2-inch nozzle. Let them sit for about 10 minutes to form a skin. Then put them in the oven and cook for 10-12 minutes. They should be set, but not dried out. Remove from oven and let cool on the baking sheet.
Make the buttercream:
Grind the nuts and the sugar in the processor as before. Cream the butter, and continue creaming as you add the nut dust. Make sure you combine them well. Sandwich the macaroons together with the buttercream.Makes about 20 cookies.