Here's the marshmallow I took.

Butter cut into small cubes. I could not stand it at room temperature. It is quite soft. Most importantly, not from the freezer.

Marshmallows put in 0.5 liter jar (note that marshmallows double) and 30 seconds in the microwave.

The marshmallow will increase in size. And then act quickly: Zephyr start whipping with a mixer, enclosing the butter piece by piece. After half of the oil involved in marshmallows, stop the mixer, put the jar with the cream in a saucepan with cold water and continuing to whisk, piece by piece add the cream and the remaining butter.

Vzbivaem five minutes. Cream keeps the shape well and is suitable for promazyvanija and decorating cakes.