Pre-heat the oven to 350°F/180 °C. Line a baking sheet with parchment paper.

In a large bowl mix together flour, baking powder, sugar, and salt.

Add eggs, vanilla extract, liqueur and mix until a dough forms. Stir in the nuts.

Divide dough into two even portions, and with slightly wet hands form 2 loaves. Place on the baking sheet and bake for 30-35 minutes, or until firm to the touch (loaves will spread during baking). Remove from oven and let cool completely on a wire rack.

Transfer loaves to a cutting board and, using a sharp knife, cut logs into slices about 2-3 mm thick on the diagonal. Place the slices of biscotti on the baking sheet and bake about 5-10 minutes or until firm to the touch.