Cut the butter into small cubes
Spread the butter out on a plate
Grate the butter using a box grater
Place the butter between two sheets of parchment paper and flatten it
Put the butter in a sealed bag and submerge it in warm water for a few minutes
Microwave it in very short bursts at low power, checking often
Place it near a warm stove or sunny window for a short time
Use a rolling pin to flatten the butter into a thin layer
Let it sit at room temperature after increasing its surface area