Boil the water in casserole.
In separate bowl, mix the cocoa powder (note: Use hot water), don’t put it yet into the caserole.
Mix the thickening flour in separate bowl (note: use cold water).
Put the brown sugar into the boiling water.
Stir continuously while boiling.
Add the mixed flour and cocoa to the boiling water in caserole.
On low heat, add the condensed milk, it may overflow.
Taste it. you may more ingredients if needed depending on your taste.
Let it cool before packaging.