Yes. Melt the butter in a large microwave safe bowl (or brown it then add it to the bowl), add the marshmallows then microwave on high for 40 seconds. Take them out and give it a good stir, then continue microwaving in 30 second increments stirring each time. After about 3 minutes the marshmallows should have lost their shape and will be really soft. Give them a quick beat with a spoon, then continue with the recipe as written. Thing won't be completely smooth and emulsified but don't worry. The next step takes care of that.