Rinse the lemons and place them in a pot. Cover with water and simmer on low heat for 1 hour. After 1 hour remove the lemons from the pot, cut them in half to remove the seeds and use a spoon to scoop out the inner flesh into a blender. Blend until the lemons have formed a puree
Place the pistachios in a food processor and grind until there are no chunky pieces and everything has ground down to a fine powder.
Preheat oven to 175 degrees celsius (350 degrees Fahrenheit). Grease a loose bottom cake pan
In a bowl combine the pureed lemon, eggs, honey, ground pistachios, almond flour, vanilla extract and baking soda. Pour into the greased cake pan
Bake for 1 hour. If the top begins to brown too quickly, cover with tinfoil. The cake will be done once a toothpick inserted into the top comes out clean.
While the cake is baking, in a small pot combine the ingredients for the lemon glaze and heat until melted. Remove from the heat and allow to cool. Pour the glaze over the top of the cake and then sprinkle with chopped pistachios