I used the proportions of another recipe and this came out pretty good. 1/2 cup butter, 1 cup brown sugar and 1/3 cup hot water. It was not as runny and thickened up a little more as it cooled.
This has a lovely taste, but my only complaint it was extremely thin - like water. It doesn't really have the texture of a "sauce". I ended up adding 3 tablespoons of flour to thicken it up and ...