This number 1 weight gaining food is great for babies 8 months to 18 months old. It’s the easiest mashed potato recipe. Learn health benefits, tips and tricks to follow when you make this creamy mashed potato recipe. This is recommended for 8months plus baby to all the ages! Even though we used Yukon gold potato to make this one the same mashed potatoes can be made with russet potatoes as well. Smooth mashed potato recipe helps the baby to eat easily and quickly. Recipe and Video by Fusion Cooking.