As soon as it's simmering, lower the heat right down and let it simmer for 1 minute.
At the end of the minute, take it off the heat, and leave to cool for 5 minutes, before we add the vodka. This is important, as we don't want the alcohol evaporating in the steaming liquid.
At the end of 5 minutes, add the vodka, stir well with a wooden spoon, cover tightly with a lid or foil, and leave to steep overnight.
500 ml 80-proof vodka (at least 40% abv)
The Next Day
Double line your funnel with your muslin cloth. If you have a large one, folding it over will work.
a large muslin cloth, a funnel
Strain your Krupnik into the sterilized bottles, pushing down only ever so slightly on the contents. Don't over do this, or your last bottle may be a touch bitter from the vanilla.
4 x 250ml
Store your Krupnik in the sealed bottles, in a dark cool place for up to a year. The Krupnik is perfectly delicious drunk immediately, but will also improve with age.