First, make your fudge. Line an 8x8" square pan with parchment and set aside. In a large pot, melt together the chocolate chips and condensed milk over medium-low heat, stirring constantly until melted and smooth. Whisk in the vanilla and pour the fudge into the prepared pan.
Let the fudge chill in the fridge for at least 4 hours or until firm. Once firm, cut into 36 equally sized squares.
Using a toothpick, skewer each piece of fudge, leaving a small piece of the toothpick exposed. Skewer a Hershey Kiss upside down (pointed side down) onto the toothpick and rest it gently against the fudge. Place on a parchment-lined baking sheet.
Melt the vanilla melting chocolate according to package directions, or until smooth. Dip each dreidel into the vanilla chocolate, coating it completely and allowing excess to drip off. Return to the parchment-lined baking sheet to set, or top with sprinkles if using. Repeat with remaining dreidels.
If piping on Hebrew letters, melt the dark chocolate according to package directions, or until smooth. Pipe Hebrew letters onto each dreidel. I find it's easiest to pour the melted dark chocolate into a small squeeze bottle with a small opening so you have more control of the chocolate. Let set, then eat!