Start by preparing the rice cakes. If you are using fresh rice cakes, separate them and rinse the rice cakes under cold water. If you are using frozen rice cakes, soak in hot water for 10 minutes. Drain and set aside.
Cook the dangmyeon and rinse in cold water. Drain and set aside.
In a large skillet over medium heat, add the neutral oil. Once the oil is hot, stir fry the onions and garlic with the vienna sausages until the onion is translucent and the slits on the sausages are opened. Add in the gochujang, gochugaru, and soy sauce and continue to sauté for a minute, to bring out the flavours.
Deglaze the pan with the milk and heavy cream, while mixing with a wooden spoon. Season with salt, pepper, and sugar.
Mix in the parmesan, rice cakes, and fish cakes and turn the heat to high. Simmer the rice cakes for 5 to 10 minutes, or until the rice cakes become malleable and the sauce thickens.
Add in the dangmyeon and give everything a good mix.
Turn off the heat, and add in the green onions.
Serve and garnish with more green onions. Enjoy!