I've used this recipe for the last six months and have gained a solid 30lbs.
Give it a try and see if it will do the same for you.

8 oz. of milk, any kind. ( i use lactose fat free milk)

8 oz. low or non fat yogurt any kind ( I use any brand that's on sale, I'm not rich you know)

20-30 grams, protein powder of your choice ( Again I use whatever brand is on sale, usually whey protein)

This shake recipe provides:
16 oz.
approximate totals:
400 calories
50 grams of carbs
40 grams of protein
4 grams of fat
Mix all ingredients in a blender or shaker cup and shake or mix for about 30 seconds. (texture preference dependent) you can add ice for texture or to thin the mix some. then serve or drink immediately. Great as a Sunday afternoon snack.
For weight gain:
I use this 2x a day morning after b'fast, and after my evening workout. It helps me recover quickly and efficiently.
I usually have strawberry flavored whey powder and throw in a strawberry banana yogurt and that really makes it tasty.
Note: Lift heavy and efficiently. Get lots of rest, and EAT!! EAT!! EAT!!
Try it for yourselves and let me know what you think.
I have more recipes like this if you'd like more.

Most of the guys at the gym think that I'm on something, cause I've gained so much weight in such a short period of time.

Cyto-Gainer (same maker as Muscle Milk) has 56 g's protein, 80 carbs, creatine, glutamine, and all the minerals. It tastes dam good with a cup of milk and its pretty cheap. Giv er a go!