Prepare a large baking sheet with parchment paper, for 18 balls.
Mix together the peanut butter and melted butter with a hand or stand mixer.
Add the powdered sugar and vanilla and mix to combine.
Mix in the rice krispies and the coconut until combined, or use a wooden spoon to really stir it well (batter will be thick).
Using a small cookie scoop, scoop the dough into your hands and roll to form a ball. Place on the parchment paper.
Place the baking sheet in the fridge for 30 minutes to chill the dough.
Melt the chocolate in the microwave until smooth on 50% heat.
Gently dip the peanut butter balls into the chocolate one at a time, using a fork to roll them so that the chocolate covers each piece, then place back onto the baking sheet.
Place the baking sheet back into the fridge and chill for at least 2 hours.
Store leftover peanut butter balls in an airtight container for several days, or in the freezer for up to 4 weeks.
TIP: You can freeze the balls BEFORE you add the chocolate, and add the chocolate later if you prefer.