Spray a 9×13 pan with cooking spray. Find a really big bowl and measure out 9 cups of cereal. Set aside.

Melt butter in a large saucepan over low heat. Cut the vanilla bean in half, and scrape the seeds with the back of a knife. Add the vanilla to the melting butter. The butter will foam and make some noise. It will bubble and crack. It will start to turn a golden brown color. Watch it carefully because it can burn very quickly. When the butter is ready, the bubbling will stop and will be brown. It takes about 5 to 7 minutes.

Add the marshmallows and salt. Stir over low heat until marshmallows are completely melted. Pour the mamarshmallow over the Rice Krispies. Coat completely with marshmallow.

Press into the prepared 9×13 pan. Let sit for 2 hours at room temperature before slicing.