Leave butter at room temperature for 30 to 60 minutes
Cut butter into small cubes
Grate cold butter using a box grater
Pound butter gently between sheets of parchment paper
Microwave in very short bursts at low power
Place butter in a sealed bag and submerge in warm water
Use a rolling pin to flatten butter between parchment sheets
Beat butter briefly with a mixer
Place butter near a warm stove or sunny spot for a short time