What are good foods to feed someone with anorexia? Very high calorie foods and meals?

Not sure if this goes in diet and fitness, or food and drink..

My younger sister has anorexia and has just moved in with me. She needs to put on about 20lbs to reach her target weight. What are good meals to cook? Foods to get her to eat?
Any help appreciated, cheers

Is there any websites with high-calorie recipes etc?