Beat the eggs with stevia using an electric mixer and slowly add melted butter. Add salt and cinnamon.
Using a whisk, Mix the heavy cream with coffee and add psyllium powder. Add this mixture to the eggs and butter and keep mixing.
Add coconut flour, ground hazelnuts and continue mixing.
At this point, mix baking soda with lemon juice, let it create foam and add it to the mixture. Mix for another 20 seconds.
Preheat the oven to 160ºC (320ºF) Pour the batter into a tray with 6 medium muffin moulds. Bake for 15 minutes.
When the muffins are ready, sprinkle them with finely ground coffee, cinnamon or powdered stevia.