Secret Easter Egg in Elden Ring

You have to fast travel to the Ninth Mt. Gelmir Campsite.

Go to Volcano Manor.

And then go to Volcano Manor Grace.

Talk to Tanith.

Join Volcano Manor.

And get the drawing-room key.

After that, you need to go to the hall towards the first door to right.

Open the door with the key.

And then bump into painting or hit it.

Lanterns are a good idea.

You have to follow the hallway and clear the monsters.

After that, go through the gate to another hallway.

Fight through more monsters in the hallway.

And get the cookbook.

Next, you have to hit the wall to go through.

Grab Depraved Perfumer Carmaan.

Hit (knock) or door 10 times.

After that, stand back and wait 10 seconds.