Wash the kabocha squash thoroughly, remove the skin, and cut into bite-sized pieces.
Cut the chicken breast into pieces suitable for eating.
Julienne the onion and green onion.
Heat olive oil in a pan and sauté the onion and green onion.
Add the chicken breast and stir-fry over high heat, then add the kabocha squash.
Pour in the spicy buldak sauce and stir-fry well to mix.
Top with mozzarella cheese, cover with a lid, and melt the cheese.
Plate the finished dish and sprinkle sesame seeds on top as desired.