Whisk milk, pumpkin, cocoa, sugar, pumpkin pie spice, and salt in a small saucepan.
Warm over medium heat, whisking often, until steaming and smooth, about 4–5 minutes. Do not boil.
Stir in chocolate chips until melted and silky, 30–60 seconds.
Remove from heat and stir in vanilla. Taste and adjust sweetness or spice.
Pour into mugs. Top with whipped cream and a light cinnamon dusting, if you like.