Preheat your oven to 180 degrees Celsius.

Sift the flour, baking powder, and salt into a bowl and set it aside.

In a mixing bowl, use a whisk attachment on medium-high speed to beat the eggs and sugar together until the mixture becomes light in color and thick, which should take about 5-6 minutes with a mixer or up to 10 minutes with a handheld mixer. This step helps create a light texture in the finished cookies.

Lower the mixer speed and gradually add the vanilla extract and the rum that the raisins have been soaking in (do not add the raisins yet). Mix until well combined.

Stir in the orange zest, followed by the raisins, ensuring everything is incorporated before turning off the mixer.

Gently fold in the flour mixture by hand, making sure there are no visible streaks of flour left. The result will be a sticky dough.

Place the dough on a baking sheet in the center of the oven and bake until it is firm and lightly golden brown, which should take about 20-25 minutes. Remember to rotate the baking sheet halfway through the baking time.

After baking, allow the dough to cool on a wire rack for 20 minutes.

Prepare two baking sheets by lining them with baking paper.

Using a sharp serrated knife, slice the log into 0.5 cm thick pieces and place them cut side down on the prepared baking sheets. A sharp serrated knife is essential for achieving thin slices without crumbling the cookies.

Return the biscotti to the oven and bake at 180 degrees Celsius until they are crisp and golden brown, which will take about 15 minutes. Rotate the sheets and flip the biscotti halfway through the baking process.

Once baked, let the biscotti cool on a wire rack. They can be stored in an airtight container for up to 2 weeks.