First, prepare the syrup. Slice half of an organic lemon and place it into a deep pot. Add stevia, vanilla extract, gelatine and water. mix well so that the gelatine dissolves. Bring it to a boil and let it simmer for 5 minutes. Set it aside to cool down. Remove the lemon slices.
In a large mixing bowl, beat the eggs with softened butter. Add stevia, lemon juice and baking soda.
Combine crushed walnuts, cinnamon, ground clove and flaxseed in another bowl and start adding this mixture to the cake batter spoon by spoon. Keep beating at a slower speed.
Grease a 25 cm cake mould with some butter and pour in the cake batter. Bake at 180ºC for 20 minutes.
When the cake is baked, stub it with a sharp knife several times so that it can "drink" the syrup.
Slowly start pouring the syrup all over the cake and let it cool down before storing it in the refrigerator. At this point, you can just decorate it with crushed walnuts for the traditional version.