S’Mores Cookie Sandwiches

Name: S'mores Cookie Sandwiches
Ingredients: Makes around 6 s'mores; For the cookies; 75 grams milk chocolate chips; 75 grams dark chocolate chips; 150 grams unsalted butter, softened; 225 grams plain flour; 75 grams caster sugar; 75 grams soft brown sugar; 1 large egg; 1/2 bicarb; 6 giant marshmallows; 50 grams milk chocolate, melted