Place the stainless steel inner pot inside the Instant Pot®, along with the noodles and water.
Close and lock the Instant Pot® lid, making sure the steam release handle is turned to Sealing. Press Pressure Cook and set time to 5 Minutes .
When done, let rest in the pot for 5 more minutes and then press Cancel and turn the venting handle to release the pressure.
Once all the pressure has been released, open the lid, drain the noodles, and set aside.
Put the stainless steel inner bot back inside the Instant Pot. Mix the noodles with the tuna, milk, salt, pepper, and beaten eggs and put the mixture in a round cake pan greased with butter. You can use the Instant Pot removable round cake pan.
Put the clean stainless steel inner pot back inside the Instant Pot. Add 1½ cups water to the Instant Pot® and insert the metal rack.
Then place the mold with the noodle mixture on the metal rack and cover with aluminum foil.
Close and lock the Instant Pot® lid. Make sure the steam release handle is turned to Sealing. Press Pressure Cook, pressure level High, and set time to 30 Minutes.
When done cooking, let the pot release steam naturally for 4 minutes. Then press Cancel and turn the steam release handle to Venting. Once all the pressure has been released, open the lid and remove the pan with the noodle cake.