You have two easy options here. First, microwave it in 10 second intervals at low power flipping it every 10 seconds until it is soft. The other option is to place your butter on a plate and fill a cereal bowl with hot water. Let the water sit in the bowl for 1 minute and then dump out the water and put the bowl upside down over the butter. This will retain heat and evenly soften your butter in about 4 minutes.