Prepare the cashew cream. Drain the cashews in a strainer. Put the rinsed nuts into a blender and add the water, agave or maple syrup, and vanilla. Blend, starting on low, and quickly increase the speed to high. Blend for about one minute, or until the cream is perfectly smooth. Push any unblended pieces of cashew down into the cream and blend for one minute longer. Add the guar gum directly into the cream, making sure it doesn't land on the sides of the container. Blend on low for 30 seconds, then increase the speed to high and blend for 1 minute. Pour the cream into a container, cover, and refrigerate for for up to three days or freeze for up to six weeks.
In a small saucepan, heat the cashew cream gently over low heat until it's just warm to the touch. Add the cocoa powder and sugar, and stir until dissolved. Remove the saucepan from heat.
Add the chocolate and the vanilla and stir until the chocolate is melted.
Spoon the warm pudding into small dishes and serve immediately, garnished with some chocolate shavings. The pudding can be made ahead and refrigerated in a covered container for up to three days. It tastes good chilled or at room temperature.