First, for the pizza base, cream together the butter and the sugar.
Next, add the egg yolk followed by the flour and combine into firm dough.
Using a paper-lined circular baking sheet as a template, roll half the dough out into a circle then prick all over with a fork. Repeat with the other half, then bake at 180 degrees celsius for 12 minutes.
Combine 150g marshmallows with 2 tbsp water and heat gently until completely melted.
Once cooled, sandwich the two ‘bases’ together using the melted marshmallow.
Spread the top with Nutella and decorate using whatever you like!