In your blender, combine the coconut milk with the spinach and blend on high power until the spinach is completely dissolved into the milk. Set aside.
In a medium saucepan, whisk the sugar, cornstarch, and salt. Add in the (very) green milk and the egg yolks. Whisk everything until combined.
Slice the vanilla beans down the center and scrape out the seeds. Put the seeds and the pods in the pan.
Now, turn the heat to medium and whisk gently as the pudding heats. Give it about 5 minutes to start heating up and getting bubbly. Don’t rush it by turning the heat up otherwise you’ll scorch the bottom of the pudding.
Once it starts to bubble, let it bubble for about a minute and then remove from the heat, take out the vanilla bean pods and gently fold in the butter.
While the pudding cools in the pan for a minute, draw the faces (or have the kids draw the faces!) on the plastic cups.
Divide the pudding among the cups (I used 4, 9 oz cups).
Cover with plastic wrap, being sure to press against the surface of the pudding so it won’t develop a skin.
Chill in the fridge for at least 3 hours. While the pudding is chilling, throw the cookies into a Ziploc bag and crush using a rolling pin.
Once the cups are cooled, top with crushed cookies, and serve to excited children (or parents).