Preheat the oven to 350F. Combine the oat and almond flours, cornflour and sea salt in a bowl. Add the coconut oil and cold water. Use your hands to work the dry ingredients together, moving in a motion towards the center a dough forms. Make a ball with the dough, wrap in saran wrap, and chill in the fridge for about 30 minutes.
Press the dough evenly into a 8 inch tart pan, making sure it is flush with the edge of the pan. Prick the bottom with a fork and blind bake for about 10 minutes and remove. Reduce the oven to 325F.
Meanwhile, whisk the eggs in a mixing bowl with the oregano, chili flakes, nutmeg and a pinch of salt and pepper. Set aside. Heat the olive oil in a frying pan on a medium-high heat. Add the leeks and cook for about 10 minutes, or until they are transparent and start to caramelize. Add the garlic and cook for 1 minute, then add in the asparagus and cook for a couple more minutes until they are bright green. Add a big handful of spinach and a pinch of salt. Stir the spinach gently until it wilts, then add another big handful and stir until wilted. Remove from the heat and pour into the mixing bowl containing the eggs. Stir well until everything is combined.
Spoon the filling into the crust. Bake for about 30 minutes until the filling is firm and golden. Let it cool for a while before serving as this will help the crust stay together and not crumble. Enjoy!