Cut the butter into small pieces
Place the butter in a microwave-safe bowl
Cover the bowl loosely with a microwave-safe cover or paper towel
Microwave on low power for 10 to 15 seconds
Check the butter and stir or rotate it
Repeat in 5 to 10 second intervals until mostly melted
Stop microwaving when a few small solid pieces remain
Stir until the remaining pieces melt from the residual heat