Wash the lemons well, then drop them whole into a pot of water. Let them simmer gently over low heat for about an hour until they've softened all the way through.

Once cooked, lift the lemons out and slice each one in half. Discard the seeds, then scoop the soft pulp and peel into a blender and puree it smooth.

While the lemons cool slightly, pulse the pistachios in a food processor until they turn into a fine, even powder with no chunks left.

Set your oven to 175°C (350°F) and lightly grease a 9-inch springform or loose-bottom cake tin.

In a large mixing bowl, whisk together the eggs and honey first, then fold in the lemon puree, ground pistachios, almond flour, vanilla, and baking soda until fully combined. Transfer the batter into the prepared tin.

Slide the cake into the oven and bake for roughly 60 minutes. Keep an eye on the top — if it's browning too fast, tent it loosely with foil. It's ready when a toothpick poked into the center pulls out clean.

While it bakes, warm the coconut oil, honey, and lemon juice together in a small saucepan just until melted and combined, then stir in the zest. Take it off the heat and let it cool slightly before drizzling it over the finished cake.

Finish with a scatter of chopped toasted pistachios on top before slicing and serving.