In a large saucepan, melt the butter over low heat. Add the marshmallows and stir until completely melted and smooth.

Remove from heat and stir in the vanilla extract.

Add the Rice Krispies and mix until well coated.

Press the mixture into a greased 9x13 inch baking dish lined with parchment paper.

In a medium saucepan, heat the sugar over medium heat, stirring constantly until it melts into a golden brown caramel.

Once melted, carefully add the cubed butter and stir until melted and combined.

Slowly pour in the heavy cream while stirring until smooth.

Remove from heat and stir in the sea salt.

Pour the salted caramel over the Rice Krispie treats in the baking dish.

Sprinkle a little extra sea salt on top for garnish.

Allow to cool completely before cutting into squares.