We make lots of variations on this....sometimes we use coconut milk other times 1% milk (once we did half and half. really. really. good). We even used greek yogurt once and I told him it was a frozen yogurt smoothie. I prefer it with milk though.
Sometimes we throw in peanuts vs. almonds. Today is the first time I added oats. And usually I add chia seed, but Tanner had a new friend over today, and I didn't want to scare him off. = )
As for the amounts....I never measure. I just throw stuff in. Plus or minus to taste. If I were to guess....maybe 1 1/2c milk, handful of oats, handful of almonds, 4t cocoa, pinch of sea salt (if you use roasted salted nuts, omit the salt), pinch of cinnamon, dates and/or agave to taste and ice to the consistency you like. Just be sure to take the pits out of the dates. I forgot once. Wow. Even my vita-mix couldn't hack that.
If there's extra shake left...throw it in popsicle molds. My kids love those too.