What date was the vanilla cake invented?

It's impossible to pinpoint an exact date for the invention of vanilla cake. Here's why:

* Cake has a long history: Cake-like baked goods have been around for centuries, with various cultures and civilizations developing their own versions.

* Vanilla is a flavor, not a unique ingredient: Vanilla is a flavoring agent, and it's been added to cakes and other baked goods for a very long time.

* Recipes evolved over time: Culinary traditions evolve and change, so the recipe for a "vanilla cake" wasn't fixed at a particular point in time.

Instead of a single date, you can think about the history of vanilla and cake coming together:

* Vanilla's introduction: Vanilla beans originated in Mexico and were introduced to Europe by the Spanish in the 16th century. They were a luxury ingredient, and their use in baking gradually spread.

* Cake's evolution: Over the centuries, cakes became more refined and techniques like leavening agents (like baking powder) made them lighter and more adaptable.

So, while we can't pinpoint a "vanilla cake invention date," we can say that the combination of vanilla flavoring with cake recipes became increasingly popular over time.