For the marinade:
Place chicken breasts in a glass oven dish or bowl together with lemon juice, a spoonful of chilli powder and salt. Stir, cover the dish and put it in the fridge for 1 hour.
Strain the yoghourt using a tea towel for 15-20 minutes.
In a medium-sized bowl, put some salt, garlic paste, garam masala, butter, chilli powder, ginger paste, lemon juice, olive oil and strained yoghurt.
Pour this mixture over the chicken, cover and refrigerate for 3-4 minutes.
Heat the oven to 200ºC.
Dice the chicken breasts and put it on skewers. Place chicken skewers on a dish and bake for 20 minutes (or until they are well done)
For the sauce:
Melt butter in a pan over medium heat. Add garam masala. When the spices are well toasted, add ginger, garlic paste and green pepper and stir well until they are soft. Next, add the tomato purée, chilli powder, salt garam masala, water and cream. Reduce the sauce over low heat stirring occasionally. When it is reduced, add the chicken.