Step 1

Spray 4 cups of a standard-size muffin pan with cooking spray.

Step 2

Place a saucepan over low heat. Add the butter and marshmallows to the pan.

Step 3

Constantly stir while melting the butter and marshmallows together into a homogenous mixture. Be careful not to let hte mixture get too hot, or the butter will cook off and the treats will be dry.

Step 4

When the mixture is smooth, stir in the rice krispie cereal. Immediately scoop the mixture into the 4 muffin cups . Smooth the surface with a non-stick spatula.

Step 5

Let cool completely, then serve.