Whisk the milk, cream, cocoa powder, sugar, vanilla, and salt in a saucepan over medium heat until smooth.
Heat the mixture until just warm, not boiling—think cozy bath water, not lava.
Remove from heat and let it cool slightly (just enough so you don’t fog up your freezer).
Pour into popsicle molds and pop them in the freezer for at least 6 hours, or overnight if you're patient.
To release, run warm water over the outside of the molds for a few seconds and gently pull out your frozen masterpiece.