Melt the chocolate with the butter in a double boiler. Preheat the oven to 160 degrees top / bottom heat.
Mix the erythritol / sugar with the almond flour / ground almonds, the chopped almonds and the baking powder. Add the eggs and mix well with the mixer. Pour in the melted chocolate and butter mixture while stirring. If you don`t use paper bags or silicone muffin molds, grease the muffin molds well (I personally use silicon molds and can`t say anything about the stickiness in paper bags or other molds, the muffins came out of the silicone molds perfectly).
Pour the batter into 6-10 muffin molds and bake in the preheated oven for about 25 minutes. Let the muffins cool a little in the molds before turning them out.
Erythritol is a sugar substitute made from sugar alcohols, without any calories or carbohydrates that our body can use. It has about 70% sweetness of sugar.
De-oiled almond flour is a sort of waste product from almond oil production and consists of the ground press cake that remains after the almond oil has been pressed out.
You can get both on the Internet, if you don`t want to save on fat and carbohydrates, just take ground almonds and normal sugar.