Preheat the oven to 180 C / Gas 4. Line a muffin tray with 12 cases and place nearby.
Melt the 3 chocolates separately over double boilers and set aside to cool slightly.
Beat one third of the butter and sugar together (50g of each) until blended. Add one of the eggs. Fold in the melted chocolate you want on the bottom layer of your muffins. Sieve in a third of the flour, baking powder and bicarb (75g, 1/2 teaspoon and 1/8 teaspoon respectively). Mix together until blended.
Spoon a dessertspoon's worth of mixture into each of the muffin cases. Top up until all the mixture is used and the cases are evenly filled.
Repeat step 3 with another third of the ingredients and use the type of chocolate you want for the middle layer. Spoon into the muffin cases, then repeat again for the final type of chocolate.
Bake in the preheated oven for around 30 minutes or until a skewer inserted near the centre comes out clean. Leave to cool on a wire rack and enjoy!
You could always make this into a large cake instead. Simply pour the mixtures into an average cake tin instead and bake for slightly longer. Or make all 3 cakes separately and sandwich together with a cream filling!