I Don't want using sugar for my toddlers snacks, but he doesn't like honey. What is the best subtitute for sweet except honey for making cake/ cookie?

My nanny makes this amazing sweet potato cake. Boil 6 Java sweet potato, puree it. Add 1/4 cup of flour and 1 egg. Beat together. Bake on 180C for 45 mins. It's super easy and delicious, and very healthy. The sweet potato adds sweetness and no sugar is needed. The adults at our house love it too!