In a bowl, add milk and yogurt and whisk to combine. Add oats, chia seeds (if using), vanilla, and cinnamon. Stir to combine. Cover and refrigerate for at least 4 hours, or overnight.
When ready to serve, give mixture a stir. Transfer to a serving glass or bowl, top with a spoonful or two of rhubarb pulp, and serve.
Notes
Cook’s Note: You can make a larger batch of this at once (2 to 3 servings), portion it out individually, and use within 3 days.