Peel the potatoes and slice into 1/2 cm slices. Place into a pan of cold salted water, and bring to the boil. Lower the heat and cook for 5 minutes, until the potato is just starting to soften but still holding its shape. Drain, then leave to one side to cool.
Spray a large frying pan with low-calorie cooking spray and set on a medium heat. Add the onions, garlic, carrot, and red pepper, and fry for 5 minutes.
Add the mince to the pan and cook until it starts to brown (about 4 minutes).
Add the courgette, mushrooms and kidney beans and fry for a further 2 minutes.
Pour in the chopped tomatoes, tomato puree, Henderson's relish, stock pot, water, and chilli powder. Simmer for 10 minutes — until the vegetables have softened, and the chilli has started to thicken. Season to taste with salt and pepper. Then preheat the oven to 190ºC.
Pour the chilli into the oven dish and top with the potato slices overlapping the edges slightly. Then spray the top with a little bit of low-calorie cooking spray.
Place the dish in the oven for 20-25 minutes, until the potato slices are golden brown. Serve with your accompaniment of choice.