In a small saucepan over medium-low heat, whisk together the milk, heavy cream, maple syrup, and cocoa powder until smooth.
Bring the mixture to a gentle simmer, whisking often.
Remove the saucepan from the heat and stir in the chocolate chips and vanilla extract until the chocolate chips are fully melted and the mixture is smooth.
Pour the mixture evenly into popsicle molds. Insert the popsicle sticks and freeze for at least 4 to 6 hours, or until fully set.