Start with less and add more. You don’t want to run out of any ingredients before all the cups have some so don’t assemble one cup at a time. Do each layer in each cup and add slightly less than you think you need. You can always come back and add more afterwards if you have extra. It is easy to overload the first few cups and then not have enough for the last ones or even to overfill the first few cups and not have enough room for the last layers!