In a saucepan, heat 500 ml of milk on medium flame until it is warm but not boiling.
In a small bowl, mix 2 tablespoons of unsweetened cocoa powder, 3 tablespoons of sugar, and a pinch of salt.
Add the cocoa mixture to the warm milk and whisk continuously until the cocoa and sugar dissolve completely.
Add 1/4 teaspoon of vanilla essence to the saucepan and mix well.
Continue to heat the mixture on low flame for 2-3 minutes, stirring occasionally.
Pour the hot chocolate into cups and serve immediately. You can top it with whipped cream or marshmallows if desired.