Preheat the oven at 250°F.
Add soft butter and sugar to a stand mixer.
Combine until smooth and fluffy.
Add one egg at a time. Incorporate fully before adding another.
Mix in vanilla essence and citrus zest.
Combine dry ingredients (flour, baking powder, cinnamon powder and nutmeg) in a separate bowl.
Add the dry ingredients a little at a time to the stand mixer.
Pour in the browning and molasses. Combine fully.
Mix in the blended fruits.
Butter two 10-inch cake pans.
Divide the batter evenly between the two cake pans.
Bake in the oven for 1 hour at 250°F.
Lower heat to 225°F.
Bake the cakes for 1½ to 2 more hours.
Check the cake for doneness (add 10 more minutes if the cakes are not fully cooked, then recheck for doneness).
Remove from oven and set aside to cool.