Add oats and chia seeds to blender; blend on high until texture of flour. Add milk to blender; use spoon or spatula to stir in oats/chias from bottom. Add yogurt. Add applesauce, peanut butter (or PB2), & cinnamon. Blend on high until desired smoothness. Taste and add sweetener, if needed. Blend again. Transfer to pint (2 cup) jar or container; refrigerate overnight, or a minimum of 4 hours, so oats & chias can soften. Will keep in refrigerator at least 2-3 days. Shake before drinking.
IF TOO THICK after the fridge soak, add more juice or milk and shake jar/container or return to blender to combine.
FOR A SMOOTHER CONSISTENCY, return to blender after the fridge soak and blend again.
TO FREEZE: May be frozen after the 4 hour soak in the fridge. To thaw, move to fridge a day ahead so it is thawed for drinking the next day. For faster thaw, place frozen jar/container in bowl of cold water on the counter for 1-2 hours. Shake before drinking.