Melt Butter: In a large saucepan over low heat, melt the butter. Once melted, add the mini marshmallows and stir until completely melted and smooth.

Combine with Cereal: Remove from heat and add the Rice Krispies cereal. Stir until the cereal is well coated with the marshmallow mixture.

Shape Treats: Allow the mixture to cool slightly, then use your hands to form small balls, about 1 inch in diameter. Place them on a parchment-lined baking sheet.

Melt Chocolate: In a microwave-safe bowl, combine the semi-sweet chocolate chips and vegetable oil. Microwave in 30-second intervals, stirring in between, until the chocolate is fully melted and smooth.

Dip Balls: Using a fork, dip each Rice Krispie ball into the melted chocolate, ensuring they are fully coated. Return them to the parchment-lined baking sheet.

Let Set: Allow the chocolate to harden at room temperature or place the baking sheet in the refrigerator for quicker setting.