In a double boiler, melt the chocolate and butter together until smooth.
Using a stand mixer (or by hand if you want the workout) mix together the eggs, sugar, and 5 grams of the cinnamon powder until a foamy mixture is created.
In another bowl sift the flour and baking powder.
Add the melted chocolate into the egg mixture. I left my stand mixer running at a decent speed to prevent the eggs from cooking. Then add the flour slowly making sure everything gets combined well.
Pour the batter into a resealable container and press down plastic wrap at the top so no part of the batter is exposed to air. Seal and place in the refrigerator for at minimum 3 hours (best overnight).
Using a teaspoon or a melon baller scoop out a tsp worth of chocolate and roll into a ball using the palms of your hands. Roll the balls in a bowl of powdered sugar and the rest of the cinnamon powder making sure every bit of the surface is coated.
Place the balls on a parchment lined baking tray and place in an oven preheated to 180 C for 10 minutes. Remove from the oven and let sit for 10 minutes on the baking tray before touching them. You can use a spatula to lift them, but they don't tend to stick, so can just use two fingers to lift them off to plate.