Make sure your free-range eggs are very fresh. Beat them with sea salt and sweetener for at least 10 minutes at high speed. You need to get a thick emulsion.
Start slowly adding melted butter as if you were making mayonnaise. Keep beating at high speed. Add baking soda.
Now add Ceylon cinnamon, coffee and cacao powder. When it's unified, stop the mixer and add the mascarpone. Start beating at a lower speed and then gradually increase the speed of your mixer until your batter is smooth.
The batter for this cake will be liquid, but since you will bake it long at low temperature, there's no reason to worry. Add the Metaxa in the end and prepare for baking.
Preheat your oven at 150ºC. grease a removable bottom cake mould (25 cm or 10-inch) with some coconut oil and pour in the batter. Bake for 1 hour and 20 minutes without opening the oven. It would be good to have a lower altitude so that the cake doesn't burn on the top.
When the cake is baked, remove it from the oven and let it cool down totally. Then sprinkle with some more Metaxa or Vanilla extract and let the cake drink it.
Using a tea strainer, sprinkle powdered stevia or monk fruit blend all over the top of the cake. Leave the cake in the refrigerator for at least 2 hours. Then sprinkle with some more powdered sweetener. This way you will get a thin layer of crunchy topping because the first layer will soak the Metaxa.
Serve well chilled, ideally on the next day after a good Keto meal! You can keep it in the refrigerator for 5-7 days.