Combine butter, 1 cup of sugar, and the corn syrup in the bowl of a stand mixer.
½ cup (1 stick) salted butter, 3 cups powdered sugar, 1 Tablespoon corn syrup
Beat on low, gradually increasing speed, until ingredients are well-combined.
Gradually add remaining powdered sugar until completely combined.
Stir in vanilla extract.
1 ½ teaspoon vanilla extract
Add heavy cream and beat until combined. Be sure to scrape the sides and bottom of the bowl so that all ingredients are well-combined.
1 Tablespoon heavy cream
Stir in sprinkles.
2 Tablespoons sprinkles
Refrigerate for one hour.
After refrigeration, roll buttercream into 1 Tablespoon-sized balls. Transfer to a wax-paper lined cookie sheet and place in the freezer to chill for 15 minutes.
When buttercream filling is nearly done chilling, prepare melting wafers according to package instructions.
1 cup dark chocolate melting wafers
Remove chilled buttercream balls and dip in melted chocolate and return to wax-paper lined cookie sheet. Immediately top with sprinkles.
Repeat until all buttercream balls have been covered. Allow to harden before enjoying.