- 1hour + 45mins
Preheat the oven to 165C and line a baking sheet with baking paper.
Step 2 Place the butter in the bowl of a stand mixer and beat for 2 minutes.
Add the sugar, with the motor running and beat for another two minutes (until pale and fluffy). Add the eggs and continue beating, scraping down the sides of the bowl with a spatula, as needed. Beat in the almond and vanilla extracts.
Add the flour, baking powder, cocoa powder and salt and beat until the mixture is just combined. Roughly chop the almonds, then stir through mixture. Lightly flour a work surface and transfer the dough to it.
Divide the dough into two equal sized lumps, and shape each into a log approximately 4cm in diameter. Place the two logs on the baking sheet, side by side. In a small bowl, beat the extra egg with a fork. Brush the logs with the egg wash and bake for about 25-35 minutes — until they feel set when touched. They should be baked all the way through. If in doubt, let them bake for a few more minutes.
Remove the logs from the oven and let cool for about five minutes on a wire rack. Wrap the logs in plastic wrap and refrigerate overnight.
Carefully slice the logs on the diagonal, into 1cm thick slices. If you choose to cut your slices thicker, note that the biscotti will be less crispy and more cookie-like.Place the slices on a baking sheet, cut side down, and bake for another 5-10 minutes (or until they are lightly toasted). Allow the biscotti to cool on the tray.