Grind the almonds, quinoa, rice and oats together in a coffee grinder or food processor until fine. There is no need to blanch the almonds because it's all going to get strained. Put the ground ingredients and the cinnamon stick in a large pot. Top with the boiling water and let sit overnight.
Blend the mixture for 3 to 5 minutes in a blender. Strain the liquid to remove the pulp. Finish with the sugar, vanilla and nutmeg before serving.