Combine oats and milk in a large bowl. Cover and let soak in the refrigerator until much of the liquid is absorbed at least 8 hours and up to 12 hours. (I let mine soak overnight.)
Preheat oven to 375 degrees Coat a 12 cup nonstick muffin tin with cooking spray
Stir eggs, maple syrup, oil, vanilla, cinnamon, baking powder and salt into the soaked oats until well combined. Divide the mixture among the muffin cups (about ¼ cup each). Top each with 1 tablespoon blueberries.
Bake the oatmeal cakes until they spring back when touched, 25 to 30 minutes. Let cool in the pan for about 10 minutes. Loosen and remove with a paring knife. Serve warm.
Notes
To Make Ahead: Wrap airtight and refrigerate for up to 2 days or freeze for up to 3 months.
Recipe by How to Have it All at https://www.howtohaveitall.net/breakfast-blueberry-oatmeal-cakes/