Step 1

Spray a 9x13 glass baking dish with cooking spray and set aside

Step 2

In a large, non-stick pot, melt butter and marshmallows on low heat, stirring constantly

Step 3

When all marshmallows are melted, remove pot from the heat and immediately stir in vanilla and protein powder, stirring quickly while marshmallow mixture is warm

Step 4

Stir in crispy rice cereal and press into the glass baking dish.   Allow bars to cool then cut and enjoy. These bars are best eaten the same day.