Put the eggs in a bowl with the sugar and whisk with wire whip, add the teaspoon of vanilla essence and then the flour. mix until mixture is homogeneous.
Flan:
First caramelize the mold and turn on the oven to 180 degrees with a pan of water inside.
Put the eggs in a bowl with sugar and beat them withwire whip until it duplicates its volume, add the cream and mix. Then add the horchata. Beat until everything is smooth. Pour the mixture into the caramelized mold and introduce in the oven for 60 minutes. After the first 15 minutes, open the oven and dump the cake mix very carefully.
If the cake browns too much, cover it with foil. A few minutes before the end of the cooking, test with a toothpick if the flan is well-cooked. If it comes out clean, the cooking must finish, otherwise leave it another few minutes.
Turn off the oven and leave in for 5 minutes, then remove and let cool at room temperature. Place in the refrigerator until the next day.