In a large microwave-safe bowl, melt the butter. 10-30 seconds.
Add the marshmallows and mix with the butter to coat the marshmallows. Then microwave 3 minutes.
Add the Golden Grahams. Use a large spoon that has been sprayed with oil to incorporate the cereal with the marshmallows.
Turn out into a 9 X 13 pan that has been sprayed on the bottom and sides with oil. Use a smaller spoon that has been sprayed with oil to spread out the mixture.