Butter an 8-inch-square baking pan. Set aside.
In a large, heavy-bottomed saucepan, melt butter over medium heat until just browned. Butter will melt, foam, and froth, then begin to brown along the bottom. Whisk browned bits off of the bottom of the pan.
Just as the butter begins to brown, add the marshmallows, peanut butter, and salt. Stir with a wooden spoon or spatula until mixture is silky smooth and speckled with browned butter bits. Remove pan from heat and add rice cereal. Quickly stir, ensuring that all of the cereal is coated in the marshmallow mixture.
Turn the mixture out into the prepared pan. With buttered or oiled fingertips, press mixture into the sides and bottom of the pan. Let cool and set for at least 30 minutes before slicing into 9 large blocks. Wrap individually in plastic wrap.
Crispy rice treats will last, well wrapped, at room temperature for up to 4 days.
From JOY THE BAKER by Joy Wilson. Copyright (c) 2012 Joy Wilson. Published by Hyperion. Available wherever books are sold. All Rights Reserved.