Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper and set them aside.
In a large mixing bowl, cream together the room temperature unsalted butter and granulated sugar using an electric mixer until the mixture is light and fluffy.
Add the eggs, orange zest, orange juice, vanilla extract, and almond extract to the creamed mixture. Beat until well combined.
In a separate bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually add this dry mixture to the wet ingredients, mixing until just combined.
Gently fold in the slivered almonds and dark chocolate chips or chunks until evenly distributed throughout the dough.
Divide the dough in half and shape each half into a log about 12 inches long and 2 inches wide on the prepared baking sheets. Make sure to leave space between the logs as they will spread during baking.
Bake the biscotti logs in the preheated oven for 25-30 minutes, or until they are golden brown and firm to the touch. Remove from the oven and let them cool for about 10 minutes.
Using a sharp knife, slice the logs diagonally into 1/2-inch thick pieces. Place the slices cut side down back on the baking sheets and return them to the oven. Bake for an additional 15-20 minutes, until the biscotti are crisp and golden.
Allow the biscotti to cool completely on a cooling rack. If desired, dip the cooled biscotti in melted dark chocolate for an extra indulgent treat.
