Heat oil in a skillet over medium heat, saute onion, garlic, and pork (if using) for 2 minutes. Add the chopped kimchi and cook for 5 more minutes until kimchi gets tender.
Add the rice and kimchi juice, stir to combine. Sprinkle sesame seeds and mix well. Remove the skillet from heat and set aside to cool down a little.
Add half the amount of cheeses to the skillet and toss to combine. Transfer the kimchi cheese mixture into a greased 9”x13” baking dish, spread the rest of cheeses on top. Bake for about 20 minutes or until the edges and the top gets golden.
Sprinkle green onion on top while it is hot. Serve hot as a side or as a main dish.