Preheat oven to 350 degrees Fahrenheit.
In a medium bowl, add almond flour, cassava flour, salt, baking soda and poppy seeds. Whisk to combine.
In a separate large bowl, add lemon juice, maple syrup, coconut oil, vanilla extract and eggs. Whisk to combine.
Fold the dry mixture into the wet mixture until a dough forms.
Add dough to a parchment lined or sprayed loaf pan and bake for 45-50 minutes.
Meanwhile, add the icing ingredients to a medium bowl and whisk to combine.
Allow the cake to cool on a cooling rack and then add icing on top. Add lemon slices to the top of your cake and enjoy!