Add 1 cup of rice and 2 cups of water to a small saucepan. Cover with a lid and bring to the boil. Once boiling, reduce the heat to low and simmer, covered, until all the water has evaporated and the rice is cooked.
Heat the butter in a small saucepan over medium-high heat. Once the butter starts to bubble, add the flour and cook, stirring, for about 30 seconds.
Stir through the curry powder and garam masala until well combined. Transfer the mixture to a bowl and set aside.
Heat the olive oil in a large frypan over medium heat. Add the garlic and onion, season with a pinch of salt and cook for 2–3 minutes, or until softened.
Stir the butter and spice mixture through the onion and garlic. Add the diced chicken and stir until well coated.
Add the tamari/soy sauce, honey, grated apple and chicken stock. Stir to combine.
Add the potatoes and carrot and bring the curry to a simmer. Reduce the heat to low and simmer for 15-20 minutes, or until the vegetables are tender and the sauce has thickened.
Spoon the Japanese chicken curry over cooked basmati rice and serve immediately.