Preheat your oven to 350°F (175°C). Line a large baking sheet with parchment paper and set aside.

In a medium bowl, whisk together the flour, sugar, baking powder, and salt.

In a separate bowl, beat the eggs lightly. Add the scraped seeds from the vanilla bean (or vanilla extract), orange zest, and orange extract (if using). Mix well to combine.

Pour the wet ingredients into the dry ingredients and stir until a dough forms. If the dough feels too dry, add a splash of milk or orange juice to bring it together.

Gently fold in the dark chocolate chunks and sliced almonds (if using).

Divide the dough into two equal portions. Shape each portion into a log about 12 inches long and 2 inches wide on the prepared baking sheet. Flatten the tops slightly.

Bake the logs in the preheated oven for 25-30 minutes, or until golden brown and firm to the touch.

Remove the baking sheet from the oven and let the logs cool for about 10 minutes. Reduce the oven temperature to 325°F (160°C).

Using a sharp serrated knife, slice the logs diagonally into 1/2-inch thick slices. Place the slices cut-side down on the baking sheet.

Return the slices to the oven and bake for an additional 10-15 minutes on each side.

Transfer the biscotti to a wire rack to cool completely.

Melt the remaining dark chocolate in a microwave-safe bowl or double boiler. Drizzle the melted chocolate over the cooled biscotti using a fork or piping bag.

Allow the chocolate to harden completely before storing or serving.