Put the milk chocolate in a sauce pan along with half of the sweetened condensed milk. Heat over medium low, stirring frequently, until melted.
Pour the chocolate into the prepared pan and refrigerate for 15 minutes.
Put the green candy melts in a sauce pan along with half of the sweetened condensed milk and the mint extract if using. Heat over medium low, stirring frequently, until melted.
Pour over top of the milk chocolate and sprinkle with the green and gold sprinkles.
Refrigerate for 45 minutes.
Pull the fudge out of the pan using the foil and cut into 25 squares.