4 tablespoons (1/2 stick) butter, plus more for greasing
2cups all-purpose flour, plus more for dusting and shaping
1 teaspoon baking powder
1/4 teaspoon salt
1cup sugar
2 eggs
1 1/2 teaspoons vanilla extract
Instructions
Heat the oven to 375°F. Grease a baking sheet with butter and dust it with flour; tap the sheet over the sink to remove excess flour.
Combine the flour, baking powder, and salt in a medium bowl.
Use an electric mixer to cream the butter and sugar in a large bowl until light and fluffy. Add the eggs one at a time, then the vanilla; beat until well blended. Add the dry ingredients to the creamed mixture a little at a time, beating until just combined.
On a well-floured surface, divide the dough in half and form each half into a loaf about 2 inches wide, 6 inches long, and 1 inch high, taking care to shape them as uniformly as possible so they bake evenly. You can lightly roll the tops with a rolling pin to smooth them out. Put the loaves a few inches apart on the prepared baking sheet and bake for 25 to 30 minutes, until they’re golden and beginning to crack on top. (Use 2 baking sheets if the loaves will crowd each other.) Cool the logs on the sheet for a few minutes, then transfer them both to a wire rack. Lower the oven temperature to 250°F.
When the loaves are cool enough to handle, carefully move them to a cutting board and use a serrated knife to slice each diagonally into 1/2-inch-thick slices. Put the cookies back on the baking sheet, cut side down; it’s okay if they are close to each other. Bake for 15 to 20 minutes, turning the biscotti halfway through baking, until they dry out. Transfer to wire racks to cool. These will keep crunchy in an airtight container for up to a week.
Spiced Biscotti: Omit the vanilla. Add 1 teaspoon ground fennel or anise seeds or 1 teaspoon ground cinnamon to the dry ingredients.
Nutty Biscotti: Reduce the vanilla to 1/2 teaspoon. At the end of Step 3, fold in 3/4 cup chopped toasted almonds, hazelnuts, walnuts, pecans, or pistachios, or whole toasted pine nuts, into the dough before shaping.
Citrusy Biscotti: Reduce the vanilla to 1/2 teaspoon. Mix 1 teaspoon minced lemon or orange zest into the dry ingredients.
Chocolate-Frosted Biscotti: Reduce the vanilla to 1/2 teaspoon. Melt 8 ounces dark chocolate with 3 tablespoons butter. Spread this mixture onto one flat surface of the biscotti when they are dry. Cool on a wire rack until the chocolate coating is firm.
Ginger Biscotti: Omit the vanilla. At the end of Step 3, fold in about 1/3 cup minced candied ginger.
Fruit Biscotti: At the end of Step 3, fold in about 1/2 cup dried fruit like raisins, cherries, or cranberries, or chopped dried apricots or figs.
Chocolate Chunk Biscotti: At the end of Step 3, fold in about 3/4 cup chopped any chocolate.