Preheat oven to 325F / 160C. Line a baking tray with parchment paper.
Simmer or steam the kale leaves for a few minutes until tender. Drain and refresh under cold water. Drain, squeeze out any excess water and puree in a food processor or with a hand held stick blender. It will still be slightly stringy. Set aside.
In a large bowl, stir together the flour, baking powder, sugar and chopped almonds.
In a separate bowl, whisk the eggs. Add the almond extract and kale and mix well. Add to the flour mixture and work into a firm dough. You may need to use floured hands.
Turn onto a lightly floured surface and shape into a log the length of the baking tray.
Place it onto the prepared tray and bake for 35-40 minutes or until it begins to turn golden. Leave the oven on.
Allow to cool for 15 minutes then cut at a slight angle into even slices ½ inch thick.
Place the slices, cut side up, onto the lined baking tray and bake again for 12 minutes. Flip each piece over and bake for a further 12 minutes. Transfer to a wire rack to cool completely. Store in an airtight container.