Preheat your oven to 190 C / Gas 5. Grease or line a muffin tin.
Sift the plain flour, caster sugar, salt, baking powder and bicarbonate of soda together in to a large bowl. Set aside.
Put the butter and the vanilla extract into a small separate bowl and mix together until creamy. Add the eggs and the mashed bananas and mix well.
Add the creamy mixture into the dry mixture and add a bit of milk each time you mix. When well combined, add the fudge chunks and the chocolate chips. Spoon into the prepared tin, filling each case half full.
Bake in the preheated oven until risen and a skewer inserted in the centre of a cupcake comes out clean, about 15 to 20 minutes,.
Remove from oven and let cool in the tin for 10 minutes before serving.