Place chopped chocolate into a medium glass mixing bowl. Set aside.
Combine heavy cream, milk, and cocoa powder in a medium saucepan over medium heat. Whisk constantly until cocoa is dissolved and mixture comes to a simmer. Remove from the heat and pour over the chocolate. Let stand for 2 to 3 minutes and then whisk gently until all chocolate is melted. Whisk in the vanilla extract.
Divide the mixture evenly among the molds and place in the freezer. Freeze until solid, at least 4 hours. Fudgepops can be held in the freezer for up to 1 week in an airtight container.