**Prepare your pan:** Grease a 9x13 inch baking dish and set aside. You can also line it with parchment paper for easy removal.

**Brown the butter:** In a large saucepan over medium heat, melt the butter. Continue cooking, stirring frequently, until the butter turns golden brown and develops a nutty aroma (about 3-5 minutes). Watch carefully to avoid burning!

**Add marshmallows:** Immediately add the marshmallows to the browned butter and stir continuously until completely melted and smooth.

**Remove from heat:** Take the pan off the stove and stir in the vanilla extract and sea salt.

**Add cereal:** Pour in the Rice Krispies cereal and fold gently until everything is evenly coated. Be careful not to crush the cereal.

**Press into pan:** Quickly transfer the mixture to your prepared pan. Using a greased spatula or your hands (lightly greased), press the mixture evenly into the pan. Don't press too hard.

**Add toppings (optional):** If you're adding chocolate chips or sprinkles, scatter them on top while the mixture is still warm.

**Let cool and cut:** Allow the treats to cool completely (about 30 minutes) before cutting into squares. This recipe makes about 24 servings.