Brown butter takes the classic Rice Krispie Treat to a whole new level. Add in sea salt and rosemary and these become irresistible. The sweet and salty combo in these Rice Krispie Squares makes this bar a perfect adult version of the simple treat.
Prepare a baking pan (approx. 13" x 9") by lining it with parchment paper or by greasing it with butter.
Make brown butter by melting butter in a very large pot over medium-high heat. Stir occasionally. The butter will melt and then bubble up, slowly starting to change colours. Watch this closely as this can go from perfect to burnt in less than a minute. When the butter reaches a golden brown colour and is fragrant, remove from heat immediately.
Stir in vanilla and marshmallows and stir continually. If the marshmallows don't melt, put the pot back on the burner on low and stir constantly until the marshmallows are smooth. Remove from heat.
Mix together cereal, salt and rosemary and add into the marshmallow mixture and stir, sitr, stir. Continue stirring until the cereal is well coated.
Gently press the cereal into the prepared baking pan. Don't push this down hard, you'll end up with rock hard squares. Just press this down gently. A trick I've learned is to dip your finger tips into water and you won't stick to the treats.
Let cool for about an hour and then cut into 24 equal squares.