Step 1

Set the oven to 175° C / 350° F (155° C / 310°F on a fan setting) and line a baking tray with a piece of baking paper.

Step 2

Place softened vegan butter and sugar in a large bowl, whip for 2 minutes until the mixture is smooth and creamy.

Step 3

Add pumpkin puree, vanilla, spices, salt, orange zest (if using). Whisk on low speed to combine. It may look like butter has split, don't worry, that's perfectly fine.

Step 4

Gradually fold in flour and baking powder until just combined. Finally add in chopped hazelnuts if using.

Step 5

Divide the dough in half - it will be sticky! - and roll each half into a rough log on a lightly floured surface.

Step 6

Transfer the rough logs onto a large baking tray and shape them into a 5 cm / 2" wide and 25 cm / 10" long logs. Refrigerate for 30 minutes.

Step 7

Place in the hot oven for about 30-35 minutes, until the log's surface is firm to a gentle pressure and lightly browned. Do not switch the oven off as these will need to be baked again. Turn the oven down a little, to 150° C / 300° F.

Step 8

Let the logs cool down for 15-20 minutes before cutting them. Cut it into 1-1½ cm / 0.4-0.5" slices with a serrated knife and a gentle back and forth sawing motion - be very gentle as the dough will still be quite fragile at this point. Place the slices on a baking tray cut side down and return them to the oven for the second bake. Bake for about 20-25 minutes, until your biscotti achieves the desired crispness and colour - remember the longer you bake them the harder they get.

Step 9

Once cool, dip the biscotti in the melted chocolate if you wish (if making them a long time in advance, skip the chocolate until closer to the consumption time as it might spoil). Arrange them on a drying rack for the chocolate to harden. Keep them in an air-tight container for 3-4 weeks or freeze.