I have gained 12kg within 7-8 months with a typical Indian diet. I was used to eat chicken, fish, milk, soay, dried fruits, mango, all kinds of nuts, and peanut butters. And for lunch and dinner I always had rice with seasonal vegetables and chicken/fish. I have also had whey and creatine and thus I was able to gain weight. You can eat these food items spanned between 5-6 meals a day and you will also be able to gain weight.