Melt the white chocolate chips in a microwave-safe bowl in 30-second intervals, stirring after each until smooth.
In a large saucepan, melt the unsalted butter and creamy peanut butter over low heat, stirring until smooth. Remove from heat and add vanilla extract and mini marshmallows, stirring until melted. Fold in Rice Krispies until coated.
Allow the mixture to cool slightly, then grease hands and roll into 1-inch balls. Place on a parchment-lined baking sheet.
Chill the balls in the refrigerator for 30 minutes to firm up.
Dip the chilled balls in melted white chocolate and place back on the parchment-lined sheet. Optionally, add sprinkles on top.
Refrigerate again until the chocolate is set.