Any healthy food can help kids to gain weight? For 1 yr old kid

My good friend's daughter was told to gain better weight too. Sometimes is is not the food we give them, it is also the timing and the way we feed them.My friend shared with me what the nutritionist advised her. Sometimes it is better to let baby try to self feed. In the process of learning to self feed they will start to have more interest in food and explore more taste. Milk needs to be cut down to about 650ml( her gal is 16 mo) Need to give three meals a day. Because my friend's daughter has milk at about 5-6am so she has no appetite for breakfast so they must start to drop the 6am milk feed or drink lesser milk. As for foods to gain weight, go for proteins like eggs, chicken, avocado, sweet potato, banana, cheese