Partially line a 20cm x 20cm baking tin with baking parchment: use 2 strips of paper, crossed over each other at right angles so that they hang over all four sides of the tin.
Break the chocolate into pieces and place in a microwave-safe bowl. Add the Carnation Caramel and stir. Microwave on medium-high for 1 minute, remove from the microwave and stir. Return the bowl to the microwave and continue to cook until the chocolate has melted.
Stir until the mixture is smooth, then add the marshmallows, mixing well. Quickly pat the mixture into the lined tin and finish by sprinkling the top with mini marshmallows. Do your best to stick them into the fudge so they set while it is in the fridge. Chill for at least 3 hours, then lift out of the tin and cut into cubes to serve.