Heat a large pot over medium-low heat. Add butter and allow to melt. Stir in marshmallows and allow to melt. Stir often. Stir in 1/4 cup of caramel sauce.
Remove from heat and pour in Rice Krispies cereal. Stir to coat together.
Pour into a parchment paper lined or greased 9 x 9 baking pan. Press into the pan with your fingers.
Sprinkle with sea salt, if so desired. Drizzle the remaining 1/4 of caramel sauce all over the top.
Let set up and cool. Cut into squares.
Notes
Butter -- for extra salty-sweet flavor, use salted butter.
Marshmallows -- use mini marshmallows in this recipe.
Rice Krispies -- use any type of crisp rice cereal like Rice Krispies.
Caramel Sauce -- I suggest using a thicker caramel sauce like you find at Trader Joe's. For a thicker caramel sauce, you can also use caramel dip.