In a large mixing bowl, beat butter, vanilla, and powdered sugar until smooth. Add in milk and beat an additional 2-3 minutes until fluffy. Cover and refrigerate for about an hour (or more!).
Scoop 1 tablespoon-sized balls onto a parchment paper-lined baking sheet. Freeze balls for about 30 minutes.
Once firm, remove balls from freezer, and use your fingertips to shape them smooth.
Melt chocolate wafers according to package directions. Using a toothpick, dip each truffle into the melted chocolate, tapping on the side of the bowl to remove the excess. Drop onto parchment paper and add sprinkles immediately. Repeat for remaining truffles.