Place the chocolate, sweetened condensed milk, cocoa and cornflour into a large sauce pan. Add 1/2 cup of your milk and mix together well. You want the cocoa and and cornflour to be completely mixed in.

Begin to heat your sauce pan on a medium-low heat, stirring regularly. Continue heating and stirring your mixture until the chocolate pieces and fully melted. Do lot let the mixture boil at any point.

Add your remaining 4 1/2 cups of milk to the saucepan and mix well.

Continue to heat your hot chocolate on a medium-low heat for about 5 minutes, stirring regularly.

Your hot chocolate will be ready when it is steaming hot and thickened enough to coat the back of a spoon.

Serve immediately topped with marshmallows, whipped cream or just as is.