In a mixer, blend butter on low speed until smooth.
Add dry mix and blend on low until a dough forms.
Refrigerate dough for 30 minutes.
Roll dough into tablespoon-sized balls and place on a parchment lined baking sheet; return to refrigerator to chill for another 30 minutes.
Microwave chocolate chips in 10-second increments until fully melted.
Use a fork to drizzle truffles with melted chocolate and sprinkle with rainbow sprinkles. (If you want your truffles extra chocolaty, dip them in the chocolate to fully coat them.)
Return truffles to parchment to allow chocolate to set completely.
Refrigerate until ready to serve.