Most days I take a shake with much along the lines what Dave suggested:
1 can light coconut milk from Trader joes
2 scoops whey protein
2-4 tablespoons of milled flax
1-2 tablespoons of greens powder
1-2 tablespoons of cocoa powder
Sometimes I'll add peanut/almont butter depending
However I'm not currently trying to gain weight I'm taking the shakes while doing IF to get all the calories I need for the day in my limited time frame.