Cut the butter into small cubes
Grate the butter using a box grater
Place the butter between two sheets of wax paper and flatten it with a rolling pin
Microwave it on low power for 5 to 10 seconds at a time
Place the butter in a warm bowl or near a warm stove
Put the butter in a sealed bag and submerge it in warm water for a few minutes
Use a warm glass or bowl to cover the butter briefly
Beat the butter with a spoon or mixer until softened