Combine the oats, the water and sweetener in a blender.
Process for 20 seconds.
Use a fine mesh sieve + a cheese cloth or a clean t-shirt to strain the milk. Avoid squeezing too much.
Notes
Xylitol can be substituted by maple syrup but it would change the colour of the milk. To keep it white and avoid additional carbohydrates, you can also use erythritol.
Store in a bottle or in a mason jar for 3-4 days.
Use the leftovers to make cookies, bars, a cake or to make an oatmeal.