If butterscotch chips are unavailable, you can use caramelized cashews instead. To do that, combine 1/4 cup of sugar and 1 tablespoon of water in a pot over medium heat, and boil until the sugar acquires a lovely golden brown color. Directly, add 1/4 cup of cashews and coat them completely in the sugar with a spatula. Place the nuts on parchment paper or a silicon sheet to cool. After the cashews have cooled, slice them up and place them in the cake mixture.