In a large mixing bowl, combine butter, corn syrup, sweetened condensed milk, vanilla, and sugar. Knead dough, and form it into balls with a cherry wrapped in the middle. The balls should be approximately the size of walnuts. Place balls in the freezer to chill.
In a double boiler, melt chocolate chips and shortening together. Dip the cooled balls in the chocolate, let cool on parchment paper.
