Lightly grease and line a 9x5 inch (2lb) loaf pan with parchment paper. Preheat your oven to 350°F (180°C).
In a large mixing bowl, cream together the softened butter (or dairy-free alternative) and granulated sugar until the mixture is light and fluffy.
Stir in the vibrant zest from two of your large lemons. Next, beat in the eggs one at a time, mixing thoroughly after each addition until fully combined into the batter.
Gently sift the gluten-free self-rising flour into the wet mixture. Carefully fold it in, then add the almond flour and continue to fold until just combined. Be mindful not to overmix to keep the cake light.
Pour the smooth cake batter evenly into your prepared loaf pan. Bake for approximately 45-50 minutes, or until a skewer inserted into the center of the cake comes out clean.
While your cake is baking, prepare the delightful drizzle. In a small bowl, combine the fresh juice from two lemons, the zest from the remaining lemon, and the demerara sugar. Stir until the sugar starts to dissolve.
As soon as the cake comes out of the oven, use a skewer or toothpick to poke numerous holes all over the top surface. Slowly and evenly pour the lemon drizzle over the hot cake, allowing it to soak deep into the sponge for ultimate moisture and flavor.
Let the cake cool completely in the pan before carefully removing and slicing. Enjoy your wonderfully zesty, moist, and healthy lemon drizzle cake!