Line 9”x9” (apx. 23x23cm) square baking pan with parchment paper. Lightly spray with cooking oil.

Measure out ingredients. Place the rice cereal in large heatproof bowl along with approximately one-third of the marshmallows mixed in. Set aside.

Melt butter in heavy-bottomed saucepan over medium heat. Reduce heat to medium-low and add the remaining two-thirds of the marshmallows. Stir until marshmallows are melted and blended with the butter.

Remove mixture from heat and stir in the vanilla. Pour mixture over the rice cereal and remaining marshmallows in the large bowl. Stir, using a greased or buttered silicone spatula, to combine ingredients then transfer mixture to prepared pan. Using the silicone spatula lightly sprayed with cooking oil (or buttered), evenly spread mixture but do not firmly pack or compress it into pan.

Let mixture set at room temperature for about 45-60 minutes before cutting into squares of desired size and enjoying.