If it's bulk you want, bulk you shall get. Try my recipe for Oatmeal Milkshakes. It's guaranteed to put mass on a pipecleaner!
Oatmeal Milkshakes
1 cup raw Quaker Oats
2 cups milk
1 overripe banana
1 raw egg * optional
dash of cinnamon * optional
Mix all ingredients into blender and liquify until smooth. Drink with a straw. The riper the banana, the more it tastes like a banana milkshake!
This shake is nutritious, delicious, and high calorie. Work up to two or three of these a day if you can handle it, and concentrate all lifts in the gym around basic exercises (squats, presses, curls, rows, dips, chins, etc).
FYI, I put on 45lbs between my junior year and senior year in high school back in 1984 when I played football. I owed the majority of my size gain to these Milkshakes. People accused me of doing steroids because I grew so fast. I took it as a compliment.