Make easy oven-baked rice crispy treats with this simple dump-and-bake method!
Preheat oven to 350 degrees F.
Grease a 9 x 13-inch baking dish really well with butter or cooking spray.
Pour the mini marshmallows evenly into the bottom of the dish.
Sprinkle the rice crispy cereal evenly over the marshmallows.
Place small pats of butter all over the top of the cereal.
Bake for about 8-10 minutes, just until the marshmallows are soft and puffed and the butter has melted. Don't let them brown.
Remove the pan from the oven. Add vanilla if desired, then stir everything together immediately, working from the bottom up until the cereal is coated with the melted marshmallow.
Gently press the mixture into the pan. Don't pack it down too firmly or the treats can become hard.
Let cool for about 30–60 minutes, then cut into squares.
For extra gooey treats: Use 10 ounces of marshmallows plus another 1-2 cups mini marshmallows stirred in after the pan comes out of the oven. That gives you those delicious pockets of soft marshmallow.