01 - In a medium saucepan, whisk together cocoa powder, sugar, and salt until thoroughly combined.
02 - Gradually add 1 cup of milk to the dry ingredients, whisking continuously until a smooth, lump-free paste forms.
03 - Pour in the remaining milk and cream, whisking constantly to fully incorporate all ingredients.
04 - Place the saucepan over medium heat. Warm the mixture, stirring constantly, until steaming and hot throughout, approximately 5-7 minutes. Do not allow to boil.
05 - Remove from heat immediately. Stir in vanilla extract until fully blended.
06 - Pour into mugs. Top with whipped cream, marshmallows, and chocolate shavings as desired. Serve immediately while hot.