Preheat your oven to 180 C. Line an oven tray with baking paper.
Mix the flour, sugar and baking powder into a large bowl. Add all the other ingredients and mix well, using your hands if needed as the mixture becomes quite stiff.
Halve the dough and form into two logs, around 5cm wide. Place on the lined oven tray.
Cook for 35 minutes, or until golden, then remove and allow to cool on the tray for 10 minutes.
Gently transfer to a cutting board and use a serrated knife to cut on a diagonal into 1 1/2 cm slices.
Reduce the heat to 160 C and arrange the slices onto the oven tray, cut sides up. Cook for another 15 minutes, or until dry and crisp.
Remove from the oven, cool, then store in airtight containers for up to 3 months.
