In a mixing bowl, combine the creamy peanut butter and powdered sugar. Mix until smooth and well combined.
Fold in the mini marshmallows until evenly distributed. Set aside.
In a double boiler or microwave-safe bowl, melt the semisweet chocolate chips with the vegetable oil, stirring until smooth and fully melted.
Using a spoon, scoop a tablespoon of the peanut butter and marshmallow mixture and form it into a ball. Repeat until all the mixture is used.
Dip each peanut butter ball into the melted chocolate, ensuring it is fully coated. Gently tap off any excess chocolate.
Place the chocolate-coated balls onto a baking sheet lined with parchment paper. While the chocolate is still wet, sprinkle pastel candy sprinkles on top.
Refrigerate the tray for about 10 minutes, or until the chocolate has hardened completely.
Once set, transfer the candies to an airtight container, separating layers with parchment paper.