1/2cup (113g) unsalted butter, at room temperature
Instructions
Slice the butter into 1/2" pieces. Place them in a large, light-colored pot.
Over low-medium heat, cook the butter until it browns (5-8 minutes); It should develop golden brown flakes and give off a nutty aroma when it's done.
Add all but 1/2 cup of the mini marshmallows. Continue cooking over low-medium heat until the marshmallows melt.
Remove from heat and add the remaining marshmallows and rice krispie cereal. Stir until evenly coated.
Pour into a buttered 8"x 8" dish or pan. Allow to set at room temperature until firm (about 1 hour).
Notes
Start with room temperature butter: This reduces the chance of splatter and helps it melt evenly.
Bringing cold butter to room temperature: One of the easiest methods is to cut it into 1/2" cubes and leave it on the counter for 10-15 minutes. You can also try one of these methods.
Cook over low-medium heat: While it may be tempting to crank your stove up to melt those marshmallows faster, this can lead to hard, dry rice krispie treats. Be sure to keep your stove at low-medium and remove immediately once melted.
Packing them into your dish: Butter the back of a small measuring cup and use it to press the rice krispies into place.
Grease your dish with butter: Cooking sprays leave a greasy residue on the rice krispie treats.
Storage: Place in an air-tight container and store at room temperature.