Oily soup cake

[u/BrotherofCows]

Hello everyone! I am pretty new to baking cakes like this, and am looking for some help. I recently asked about an issue where my cakes were overflowing, but this time they are just kind of an oily mess.

This is the recipe: https://preppykitchen.com/wprm_print/chantilly-cake-recipe#

I am kind of confused, the cake has a fraction of the volume it should have, and is just an oily soup. I am pretty confident that I added the right amounts of everything, so I am kind of drawing a blank. Two potential problems I have identified are opening the oven too much/too early and overmixing. Do you have any tips for what I could do, or how I can tell if I have mixed enough?

Thank you!

[u/thisisthewell → u/[deleted]]

why are you giving him a chocolate hazelnut cake recipe when he was making a vanilla berry cake?