Steps

1. Thinly slice half of the onion (1/2 pc).
   🕒 00:42
2. Finely mince the remaining half of the onion.
   🕒 01:04
3. Crush the stems of the mushrooms (3-4 pcs) and tear them into small pieces by hand. [Key Tip!] Tearing them smaller helps them blend well into the white sauce, releasing more aroma and flavor.
   🕒 01:24
4. Cut the chicken thighs (200-250g) into bite-sized, easy-to-eat pieces.
   🕒 01:59
5. Season the cut chicken thighs with salt (1/3 tsp) and rub it in.
   🕒 02:36
6. Heat butter (to taste) in a frying pan and sauté the sliced onion until softened.
   🕒 02:50
7. Add the warm cooked rice (400g) to the softened onion and stir-fry until the moisture evaporates.
   🕒 03:11
8. Stir in the ketchup (4-5 tbsp) and cook until evenly coated.
   🕒 03:26
9. Finish by adding butter (to taste) to enhance the aroma. [Key Tip!] Adding extra butter at the end is optional for richer flavor.
   🕒 03:40
10. Divide the prepared ketchup rice evenly into two heatproof containers.
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11. Without washing the frying pan used for the ketchup rice, heat butter (to taste) in it.
    🕒 04:30
12. Add the chicken thighs, minced onion, and torn mushrooms and stir-fry briefly. [Key Tip!] Maximize the flavor from the chicken.
    🕒 04:52
13. Once the chicken changes color and the onion is softened, add all-purpose flour (2 tbsp) and stir to coat the ingredients. [Key Tip!] Thoroughly coating the ingredients with flour prevents lumps from forming.
    🕒 05:23
14. When the floury smell disappears, gradually add the milk (400ml) in 2-3 additions, stirring as you go. [Key Tip!] Adding all the milk at once can cause lumps, so add it in stages.
    🕒 05:49
15. As it starts to thicken, reduce the heat to low, add the remaining salt, and simmer on low heat until it reaches your desired consistency. [Key Tip!] Adjust the thickness to your preference. A slightly thinner sauce will soak into the ketchup rice better.
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16. Generously pour the white sauce over the ketchup rice in the containers.
    🕒 07:06
17. Sprinkle a generous amount of shredded mozzarella cheese (for melting) over the top. [Key Tip!] Leaving a little of the ketchup rice visible on the edges makes for a cute presentation.
    🕒 07:17
18. Bake in a toaster oven until the surface is golden brown and slightly crispy.
    🕒 07:27