To make sweet potato rosti, wash and squeeze grated sweet potato to remove as much moisture and starch as possible. Add crushed peppercorns and mix well.
Heat ghee and sunflower oil in a non-stick pan. Add sweet potato mixture and gently push down to make a compact cake, using the back of the spoon. Fry the rosti for 5 minutes on each side or till it turns golden and crisp on both sides. Sprinkle salt and remove from heat. Drain on absorbent paper, cut into rectangles and set aside.
To make sweet potato falafel, grind together the water chestnuts and chickpeas into a coarse mixture.
Take the mashed sweet potatoes in a bowl. Add the ground mixture, garlic, chopped coriander, salt, crushed peppercorns, chilli flakes, cumin seeds and cranberries. Mix well. Divide the mixture into equal portions and shape them into medium size patties or falafels.
Heat some oil in a non-stick pan. Place the falafels on it and shallow-fry till golden and evenly done from both sides. Drain on absorbent paper and set aside.
To make sweet potato filling, heat ghee in a non-stick pan. Add cumin seeds and sauté for half a minute. Add red chilli flakes, sweet potatoes and toss to mix.
Add salt and mix well. Add cream, mix well and switch off heat. Add chopped coriander and mix well. Set aside.
To make cheese sauce, combine Philadelphia cheese, cheese spread, cream, salt, chilli flakes and Cajun spice in a bowl and mix well.
Heat 2 teaspoons olive oil in a non-stick pan. Add cherry tomatoes and grill till done. Remove from heat and set aside.
To serve, spread a spoonful of the tomato-basil sauce on a serving plate. Place a rosti on it. Top with falafels and pipe out some cheese sauce on top. Place another rosti on top and top with sweet potato filling. Put another rosti on top and place a cheese sauce quennel on top. Garnish with a coriander sprig. Tear some lettuce leaves and place on the side of the mille feuille. Put grilled cherry tomatoes in it and serve immediately.