In a mixing bowl, combine the peanut butter, softened butter and powdered sugar.
Mix until the ingredients are thoroughly combined and form a smooth, dough-like mixture.
Take small portions of the mixture and roll them into balls about 1-inch in size. Place these balls on a baking sheet lined with parchment paper. Refrigerate for 30-60 minutes.
Melt the semi-sweet chocolate in the microwave in 30-second intervals, stirring each time until smooth. Alternatively, use a double boiler for a gentle, even melt.
Using a fork or toothpick, dip each peanut butter ball into the melted chocolate, ensuring it's completely coated.
Place the coated balls back onto the parchment-lined baking sheet.
Once all the balls are coated, refrigerate them for about an hour or until the chocolate hardens.