Line your 9×9 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal, and lightly grease the paper with butter or non-stick spray.

Melt the 4 tablespoons of butter in the large saucepan over low heat until completely liquefied.

Add 8 ounces of the miniature marshmallows to the butter, stirring constantly with a silicone spatula until the mixture is completely smooth and no lumps remain.

Remove the pan from the heat immediately and stir in the vanilla extract and your chosen gel food colouring, if using, until the colour is uniform.

Fold in the crispy rice cereal, stirring gently until every piece is evenly coated in the melted marshmallow mixture.

Stir in the remaining 2 ounces of whole marshmallows and the candy-coated chocolates, being careful not to over-mix so the marshmallows keep their shape.

Transfer the mixture to your prepared baking pan, using your greased spatula to press it down gently into an even layer; do not pack it too tightly or the bars will become hard.

Scatter the festive sprinkles over the top, pressing them lightly into the surface so they adhere.

Allow the treats to cool completely at room temperature for at least 30 minutes before lifting them out of the pan using the parchment paper handles.

Use a sharp, greased knife to cut the block into 16 even squares.