Should I start drinking Ensure Plus?

I'm trying to gain weight over the summer. I already know to eat the healthy foods (nuts, pasta, fruit, etc.) but I honestly don't think just that will work for me. Should I drink ensure plus, and if so how many do I drink to gain weight? I only want to gain around 12-15 pounds this summer. Is ensure plus dangerous to my health or anything? I don't want to die xD.