Preheat the oven to 180°C/350°F and line a muffin tray with silicone cupcake moulds or patty pans.
In a large bowl, cream together the softened butter and brown sugar.
Add one egg, beating well, then add the second egg and beat again until combined.
Sift the flour and baking soda into the bowl.
In a small bowl, mash the bananas until softened.
Add the mashed bananas and milk, then gently fold through.
Add the boiling water and gently fold through the mixture.
If using, add the chocolate chips or chocolate buttons and gently fold through.
Scoop the mixture into the prepared moulds, filling each three-quarters full. Makes 12 regular-sized muffins.
Bake for 20–22 minutes, until a skewer inserted into the centre comes out clean.
Leave to cool in the tray for 10 minutes, then transfer to a cooling rack.
Once cooled, store in a well-sealed container.