Rinse the chicken, pat dry, remove the skin and place in a bowl with the lemon juice. Refrigerate and 30 minutes. Peel and finely chop the garlic. Place the cumin and coriander in a mortar and coarsely grind. Heat 2 teaspoons of the ghee in a skillet, and briefly saute the cumin, coriander and garlic. Stir in the turmeric and cayenne pepper and remove from heat and transfer to a bowl. Stir in the yogurt, paprika and curry paste to taste and season with salt.
Pour the yogurt mixture over the chicken, cover and refrigerate overnight.
The next day, preheat the oven to 200°C (approximately 390°F).
Place the chicken with the yogurt marinade on an oiled baking sheet, cover with the remaining ghee, place in the oven and bake until the chicken is cooked through, 25-35 minutes.