Start by placing your butter, dulce de leche and mini marshmallows into a saucepan over a low heat, stirring constantly until melted and fully combined.
Gently heat for 10-15 minutes until melted. Once combined and looking gorgeous and velvety, add the cinnamon, vanilla extract and a pinch of fine sea salt, stir to combine.
Remove the pan from the heat and fold in the rice krispies until everything is well coated and glossy with the caramel sauce.
Pour this mixture into the prepared pan and very gently use the back of a spoon to coax the mixture into the corners. It is very sticky and you don’t want to crush all the rice krispies.