In a medium bowl, mix powdered sugar, softened butter, milk, and vanilla extract until a dough forms. If the mixture is too sticky, gradually add more powdered sugar until it is pliable.
Take a small amount of the sugar dough and flatten it into a disc. Wrap each cherry in the dough, completely encasing the fruit. Place on a parchment-lined tray with the stems pointing up.
Melt the dark chocolate in a heatproof bowl set over a pot of simmering water, stirring until smooth. Alternatively, melt in the microwave in 30-second bursts, stirring between each burst.
Dip each dough-wrapped cherry into the melted chocolate by holding the stem. Allow excess chocolate to drip off, then place back on the parchment paper. Chill the chocolate-covered cherries until set, about 30 minutes to 1 hour.