In a large mixing bowl, stir together the peanut butter, softened butter, vanilla, and salt.
Add the powdered sugar a bit at a time, mixing until a thick dough forms. It's okay if it gets a little crumbly—just keep pressing it together with your hands.
Roll the dough into small 1-inch balls and place them on a parchment-lined baking sheet.
Pop them in the freezer for 20 minutes so they firm up.
While they chill, melt the chocolate chips (and coconut oil if using) in a microwave-safe bowl, stirring every 30 seconds until smooth.
Dip each peanut butter ball into the melted chocolate using a fork or toothpick. Let excess chocolate drip off before returning to the baking sheet.
Refrigerate until the chocolate hardens—about 10 minutes—and you're done!