Toast the Nuts (Optional but Recommended): Place nuts in a single layer in a large, dry skillet over medium heat. Toast for 5-7 minutes, stirring every 20-30 seconds, until fragrant and lightly golden. Immediately transfer to a cutting board to cool completely, then coarsely chop.

Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

Cream Butter and Sugar: In the bowl of a stand mixer fitted with the paddle attachment (or using a hand mixer), cream the softened butter and granulated sugar on medium-high speed for about 3 minutes, until light and well combined.

Add Wet Ingredients: Beat in the vanilla extract. Add the eggs one at a time, mixing well after each addition and scraping down the bowl as needed, until the mixture is smooth and blended.

Combine and Add Nuts: With the mixer on low, gradually add the flour mixture, mixing until just combined. The dough will be tacky. Gently fold in the chopped nuts with a spatula until they are evenly dispersed. Do not overmix.

First Bake: Preheat your oven to 350°F (175°C). Line a large baking sheet with parchment paper. Divide the dough into three equal pieces. With lightly floured hands, shape each piece into a log approximately 9 inches long, 3 inches wide, and 3/4 inch thick. Place the logs about 2 inches apart on the prepared baking sheet. Bake for 25-28 minutes, or until the logs are just starting to turn golden at the edges.

Slice the Biscotti: Remove the logs from the oven and let them cool on the baking sheet for about 10 minutes. Carefully transfer the warm logs to a cutting board. Using a sharp serrated knife, slice each log diagonally into 1-inch wide pieces.

Second Bake: Arrange the biscotti slices cut-side down on the same parchment-lined baking sheet (you may need two sheets). Bake again at 350°F (175°C) for 15-18 minutes, or until the cookies are golden and firm to the touch. They will continue to harden as they cool.

Cool and Finish: Transfer the biscotti to a wire rack to cool completely. If using, melt the chocolate chips in a microwave-safe bowl in 15-second intervals, stirring until smooth. Drizzle the melted chocolate over the cooled biscotti or dip one end. Let the chocolate set completely at room temperature before serving or storing.