In a medium saucepan, combine cocoa powder, flour, and sugar.
Add a pinch of salt to the dry mixture.
Gradually whisk in the milk until smooth.
Place the saucepan over medium heat and stir continuously.
Cook until the mixture starts to thicken, about 5-7 minutes.
Once thickened, remove from heat and stir in the butter.
Add vanilla extract and mix well.
Serve warm over freshly baked biscuits or pancakes.
Enjoy your delicious chocolate gravy!