Preheat the oven to 350°F. Grease a 9x5-inch loaf pan and line it with parchment paper.
Blend the cottage cheese until completely smooth. In a large bowl, whisk the blended cottage cheese, eggs, melted butter, lemon zest, lemon juice and vanilla until creamy.
In a separate bowl, whisk together the almond flour, coconut flour, sweetener, baking powder and salt.
Add the dry ingredients to the wet ingredients and stir until a thick, smooth batter forms. Spread it evenly into the loaf pan.
Bake for 45 to 55 minutes, until golden and a toothpick inserted in the center comes out clean.If the top browns too quickly, loosely cover it with foil after 25 minutes.
While the cake is still warm, poke holes across the top with a skewer. Let it cool in the pan for 15 minutes, then transfer to a wire rack.
Whisk the powdered sweetener with the lemon juice until smooth and pourable. Drizzle over the cooled cake and let it set for 15 minutes before slicing.