2 cups spinach
1 ripe banana
1/4 to 1/2 cup frozen pineapple
1/4 to 1/2 cup water (depending on how thick you want it!)
1) Throw everything in a blender and blend for about a minute. If using frozen pineapple, you should make sure that this is closest to the blade so that it blends well.
After a while, you'll probably ween yourself off of needing the pineapple. But if you do, you may want to start freezing bananas to get that consistency the frozen fruit adds.
Source of recipe: Modified from various ideas. I didn't like adding sugar or stevia or juice or agave like the other recipes. This is totally sweet enough on it's own.