Cocoa from cocoa powder, quantity one. Half the normal sugar, partly because “normal” is too sweet, but mostly because I add a shot of creme de menthe or something to it usually and that adds a lot of sugar.
Recording it here because it’s annoying to deal with reducing recipes for such small quantities.
Mix dry ingredients in sauce pan. Add water and whisk while heating. Heat to boiling, boil for two minutes. Then add the milk while stirring. Heat to just short of boiling.
Add liqueur to cup (1 to 1.5 oz is often good). Pour in cocoa. This all neatly fits in all my mugs (in my big mugs it’s considerably less than a full mug).
There’s probably an even easier way in the microwave, but I haven’t worked that out (the timing is rather critical, and specific to the microwave).