Line an 8x8 baking pan with wax paper, spray wax paper with cooking spray and set aside.

Combine peanut butter and vanilla in a medium pot sprayed with olive oil spray. Heat over medium-low heat, stirring to prevent burning.

Add marshmallows, continuing to stir until marshmallows melt and blend with peanut butter.

In a large mixing bowl pour peanut butter/marshmallow mixture over Rice Krispies and stir until completely coated.

Press cereal mixture into lined 8x8 pan and cool in refrigerator 30 minutes before cutting and serving.