Step 1: In a medium saucepan, combine the cocoa powder, granulated sugar, and salt. Whisk vigorously to break up any lumps and ensure the dry ingredients are well combined.
Step 2: Pour in 1/4 cup of the milk. Whisk continuously until a smooth, thick paste forms. This step is crucial for preventing lumps in your hot chocolate.
Step 3: Gradually add the remaining 3 3/4 cups of milk to the paste, whisking constantly until fully incorporated and smooth.
Step 4: Place the saucepan over medium heat. Heat the mixture gently, stirring occasionally with a whisk, until it is steaming and hot to the touch. Do not allow the mixture to boil, as this can scorch the milk and affect the flavor. Look for small bubbles forming around the edges of the pan.
Step 5: Once heated, remove the saucepan from the heat. Stir in the vanilla extract.
Step 6: Taste your homemade hot chocolate and adjust sweetness or chocolate intensity as desired by adding a small amount of extra sugar or cocoa powder, whisking until dissolved.
Step 7: Pour the hot chocolate into mugs. Serve immediately with your favorite toppings such as whipped cream, marshmallows, chocolate shavings, or a sprinkle of cinnamon.