In a mixer bowl, beat peanut butter and butter. Stir in vanilla. Add powdered sugar and beat on low speed until smooth.
Roll into 1 inch balls and place in the freezer for at least one hour.
Place the chocolate in a deep bowl and microwave for 10-15 seconds at a time, stirring between intervals, until melted.
Dip the chilled peanut butter balls 3/4 of the way into the melted chocolate and place on wax paper.