In a large bowl, mix the peanut butter with the melted butter until smooth.
Add in the powdered sugar a cup at a time, mixing until well blended.
Place the mixture in the fridge for 15 minutes to chill. This makes it easier to roll.
Roll the peanut butter mixture into balls about 1 inch diameter and place on a baking sheet lined with parchment paper or a silicone liner.
Place the peanut butter balls in the fridge or freezer for 15 minutes to chill before coating in chocolate.
Place the chocolate in a microwave safe bowl and microwave in 20 second intervals, stirring between each interval until the chocolate is melted and smooth. If you want to colour your chocolate you can add a couple of drops of gel food colouring, after the chocolate is melted, until you reach your desired colour.You can also use a double boiler on the stove. Heat water in the bottom portion of the double boiler over low heat, when the water is simmering, add the top piece and add the chocolate. Stir until melted and smooth.
Working one at a time, dip each ball in the melted chocolate and gently roll the ball until it is coated. I use a chocolate decorating tool, but you can use a fork, skewers and chopsticks also work well.
Once the peanut butter ball is coated, carefully lift it out of the chocoalte and return it to the tray. If you are going to add decorations, like sprinkles or eyes, do so while the chocolate is still warm.
Allow the chocolate to set (this should only take about 15 mintues at room temperature) then move to airtight continer for storage.