Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat to prevent sticking and ensure even baking.
In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy. This usually takes about 2-3 minutes using an electric mixer on medium speed.
Crack in the eggs one at a time, beating well after each addition. Stir in the vanilla extract and freshly grated orange zest to infuse the dough with vibrant citrus aroma.
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. Avoid overmixing to keep the biscotti tender yet crisp.
Gently fold in the dried cranberries and chopped candied orange peel, distributing them evenly throughout the dough for consistent flavor in every bite.
Divide the dough in half. On your prepared baking sheet, shape each half into a log about 12 inches long and 2 inches wide. Press gently to flatten the tops slightly for even baking.
Bake the logs for 25-30 minutes, or until golden brown and firm to the touch. Remove from the oven and let cool for about 10 minutes. This first bake sets the shape and partially cooks the biscotti.
Using a sharp serrated knife, slice each log diagonally into 1/2-inch thick slices. Lay the slices cut side down on the baking sheet. Bake for an additional 10-15 minutes, turning once halfway through, until crisp and lightly browned. This twice-baking process creates the signature biscotti crunch.
Transfer the biscotti to a cooling rack and let cool completely. Once cooled, they are ready to enjoy alongside your favorite hot beverage or to package for gifting.