Eating calorie dense foods thinking that it would lead to weight gain is not correct. You must:-
a) Set your metabolism levels right by following a strict dietary regime and setting your body clock right
b) Include foods that are nutrition as well as calorie dense
c) include some physical activity in your daily routine (at least 30mins/day)
Next Steps
From activities like climbing stairs to brisk walking, gradually increase your activity levels. Include things like almond and banana shake in your diet, add dates to it. Add roasted sesame seeds to your vegetables. For more action points, you can contact me on direct consult or visit me to get a customised diet plan suiting your needs.