Note: Biscotti is perfect to have with coffee. It also freezes really well so if you make too much you don't have to feel obliged to eat all of it... unless you want to!
6 tablespoons unsalted butter, cut up, at room temperature
3/4 cup granulated sugar
1 teaspoon vanilla extract
2 teaspoons grated lemon zest
2 1/4 cups all-purpose flour
1 1/2 teaspoons baking powder
1/2 teaspoon salt
1 cup macadamia nuts, coarsely chopped
Preheat the oven to 350°F. Grease and flour a baking sheet. In a large bowl, with an electric mixer on high, beat the butter and sugar until pale and creamy. Beat in the eggs, vanilla, and lemon zest. Add the flour, baking powder, and salt. Blend to combine. Stir in the nuts. Halve the dough and, with lightly oiled hands, roll each half into a log about 2 inches thick and 12 inches long. Place the logs on the baking sheet and bake in the center of the oven for 25 minutes, or until golden.
Remove the baking sheet from the oven and place on a rack to cool. Transfer the logs to a breadboard. Using a serrated knife, slice them about 3/4 inch thick at a 45 degree angle. To avoid crumbling, use firm, decisive strokes. Place the slices flat on a baking sheet and return to a 350°F oven for about 10 minutes, turning once, to dry them. Cool on a rack. The cookies will keep in an airtight container for two to three weeks.