Grease a 9 x 13 inch pan with softened butter.
In a large non-stick saucepan, melt butter over medium heat stirring constantly until slightly golden and fragrant. There should be little brown flecks throughout the butter
Add marshmallows and stir until completely melted. Remove from heat
Add vanilla bean and stir completely
Add cereal. Stir until well coated
Using buttered spatula or wax paper evenly press mixture into a 9 x 13 inch pan greased with butter. Sprinkle with Maldon salt if using
Cool. Cut into 2-inch squares using a knife sprayed with cooking spray or coated with softened butter.
Eat right away or wrap each square tightly with cling wrap.
