Place a small ramekin, topside down, inside a small bowl wide enough to fit the top of each serving glass, as shown.
Pour the mini chocolate chips around the ramekin. If a ramekin is unavailable, add one-half cup of chocolate chips directly to the bowl. Microwave on 50% power just until the chips melt, approximately 2-3 minutes. Check after 90 seconds to determine the total microwave time needed.
Remove the chocolate from the microwave and carefully break up any remaining solid pieces with a fork.
Dip the tops of each glass into the melted chocolate, and then roll the chocolate-coated edge in the rainbow sprinkles. Roll each glass edge until completely coated. Turn upright and set aside to dry.
Add the ice cream, vanilla extract, and milk to a blender and blend until smooth. Add a little additional milk to reach the desired consistency, if desired.
To serve, pour the milkshake into the prepared glasses and top with whipped cream, additional sprinkles, and a maraschino cherry. Enjoy!