Measure the Scotch whisky in a toddy glass. Place brown sugar or honey in a measuring cup or other heatproof small container. Spoon in butter, and pour on 2 oz (1/3) of the hot water; stir till butter and sugar are completely dissolved into a syrupy consistency (about 30 secs). Pour on the rest of the water, stir briefly, then pour the works on top of the Scotch. Stir gently; serve.