1. Preheat oven to 175 C/350 F. Line a baking sheet with parchment paper.
2. In a medium-sized bowl, mix together the flour, sugars, ground almonds, baking powder, salt and cinnamon. Set aside.
3.In a blender, puree the tofu until creamy and slightly fluffy (mixture should equal about ½ cup once processed). Add the ground flax seeds, soy or almond milk, lemon juice and vanilla extract to the mixture, and puree until well combined.
4. Add the tofu mixture to the dry ingredients, mixing until forming a sticky dough. Turn the dough out onto a well floured surface, and form the dough into two logs with rounded ends.
5. Bake the logs on prepared sheet for 35 minutes, or until golden brown. Remove the logs from the pan and let rest on a cooling rack for 15 minutes. Turn down the oven temperature to 150 C/300 F.
6. Slice the logs diagonally in pieces 1 1/2 cm- 2 1/2 cm thick and lay biscotti on their sides on the prepared pan. Bake for 25-30 minutes, flipping the biscotti with a metal spatula half-way through to ensure even baking. Biscotti should be lightly golden but not browned; they will be hard if over-baked. Biscotti will keep up to two weeks in an airtight container.