melt the chocolate
Preheat the oven to 180 °C / 350 °F. Melt 125 g / 4.4 oz of chocolate and butter in a glass bowl over a pan of simmering water, stiring occasionally. When the chocolate melts completely, stir in the sugar, set aside and let cool for 10 minutes.TipDo not allow the base of the glass bowl touch the water.
combine all ingredients
Beat in the eggs one by one, with electric hand mixer or whisk, beating for 30 seconds between each addition. In another bowl combine flour, cocoa powder, baking soda and salt. Stiff dry ingredients into a bowl and beat until well combined, for about 1 minute. Chop the rest of the chocolate (or use any other chocolate, like white chocolate or milk chocolate) into small chunks and add to the bowl. Stir well, using a spatula so that the chocolate is evenly spread.
Davide the mixture between muffin cases and bake in a preheated oven for about 25 minutes if you are making large muffins or 20 minutes if you are baking small muffins or until well risen. Remove from the oven and let cool completely on a wire rack if possible.TipTo be sure that the muffins are baked put the skewer in the center of a muffin. It should come out clean.