Boil the noodles according to package instructions and drain them.
Heat oil in a pan over medium heat and sauté the garlic and chili flakes until fragrant.
Add soy sauce and chili sauce and stir for a few seconds.
Pour in the milk and butter and stir until combined.
Add shredded cheddar and mozzarella cheese and stir until melted and creamy.
Add the cooked noodles to the pan and toss until fully coated in the cheesy spicy sauce.
Season with salt and black pepper and mix well.
Garnish with green onions and sesame seeds before serving.
Add sriracha or extra chili sauce for more heat if desired.
Serve hot and enjoy immediately.