What is a nanalan cake?

There's no known or established cake called a "nanalan cake" in standard baking or culinary traditions. It's possible:

• It's a regional or family recipe: The name might be unique to a specific region, culture, or family. If you heard it from someone, asking them for the recipe or more details about its origin would be the best way to learn more.
• It's a misspelling or a variation of a different name: Could it be a misspelling of another cake? Perhaps a slight alteration of a name you've heard before? Try searching for similar-sounding names.
• It's a newly invented cake: Someone may have recently created a recipe and given it this name.

Without more information, it's impossible to provide details about a "nanalan cake."