I highly recommend using a scale for this recipe. You will also need a hand mixer for the recipe.
You can also divide the cake recipe in two to make a one layer cake but would encourage you to mix the jam with the frosting for an easier cake decorating experience
Feel free to adjust the spices to your personal preference. There are no substitutions for the calabash nutmeg because of its unique flavour profile so it can be omitted. Nutmeg has a different flavour and aroma that calabash nutmeg
I will also recommend using piping bags and an offset spatula for the frosting process. You can make makeshift piping bags from ziplock bags.