- 4 tablespoons butter, softened, plus more for greasing the pans
- 3/4 cup sugar
- 2 eggs
- 1 teaspoon vanilla extract
- 2 cups all-purpose flour, plus more for dusting the pans
- 1 teaspoon baking powder
- 1 cup blanched hazelnuts, toasted and chopped
- Pinch salt
- Heat the oven to 375 F.
- Grease a baking sheet with some butter and dust it with flour; turn the sheet upside down over the sink and tap to remove the excess flour.
- Use an electric mixer to cream together the 1/2 stick butter and the sugar until light and fluffy; add the eggs, one at a time, and beat until well blended, then add the vanilla.
- Combine the flour, baking powder, nuts, and salt in a bowl.
- Add the dry ingredients to the egg-butter mixture at a time, beating until combined.
- Divide the dough in half, roll each half into a loaf 2 inches wide, and put on the prepared baking sheet.
- Bake for 25 to 30 minutes, rotating the position of the pan in the oven if necessary so they cook evenly, until they are golden and beginning to crack on top.
- Cool the logs on the sheets for a few minutes, then transfer to a rack.
- Lower the oven temperature to 250 F.
- When the loaves are cool enough to handle, transfer them to a cutting board and use a serrated knife to slice each on the diagonal into 1/2-inch-thick slices.
- Put the cookies on the sheet, sliced side up; it's okay if they are close to each other.
- Return the pan to the oven, and bake 15 to 20 minutes, turning the biscotti once, until they dry out.
- Cool them on racks.
- They will keep in an airtight container for several days.