Step 1

Grease an 8-inch square baking pan with cooking spray or butter and set aside.

Step 2

Place the butter in a light-colored saucepan over medium heat. Heat the butter, swirling the pan and occasionally stirring with a spatula. The butter will foam, turn a caramel color, and then turn a dark brown color. Watch so the butter does not burn.

Step 3

Add the marshmallows to the saucepan and turn the heat to medium low. Heat until the marshmallows melt and the mixture is smooth, frequently stirring.

Step 4

Have the Rice Krispies ready in a large bowl. Pour the marshmallow and butter mixture over the cereal. Fold together with a spatula and transfer to the baking dish.

Step 5

Use a clean spatula to press the treats evenly in the pan. Let cool completely, about 2 hours.

Step 6

Cut into 2-inch squares.