This is the final sidequest in Koko's sidequest chain. Complete "Koko Cuisine" first before you can speak to her again (if it's between noon and 7:00 PM and not raining) for this one. Learn more about "Koko Cuisine here.
Koko now wants to make a dessert dish for the family. But she doesn't have Courser Bee Honey. You can find this honey by knocking down trees that have beehives in them. For example you can find plenty around the Hateno Fort. Just be careful, because bees do guard their honey and will attack you.
Bring her one Courser Bee Honey. She will share the dish, Energizing Honeyed Apple, with you as your reward. The recipe will be recorded in your Adventure Log if you ever forget it. Cook apples and courser bee honey together to recreate this recipe.
With this, the Koko sidequest chain is complete.