Preheat oven to 450° F and spray a 12-muffin tin with cooking spray or line with cupcake liners.
Add oats to a blender and blend into a flour.
Add in the rest of the ingredients and blend just until smooth, about 20 seconds, stopping to scrape the sides of the blender as needed. Once mixed, use a rubber spatula to give the mixture a quick stir to make sure you incorporated everything off the bottom and sides of the blender.
Using a cookie scoop, fill each muffin cavity about 2/3 full. Sprinkle each with a few rolled oats if desired.
Bake at 450° for 5 minutes to help the muffins rise. After 5 minutes, lower the temperature to 350° and bake for another 11-12 minutes.
Insert a toothpick into the center of a muffin to ensure it comes out clean. Add an additional minute of baking time as needed until cooked through.
Allow the muffins to cool for 5 minutes, then transfer to a cooling rack to cool completely.
Enjoy warm, or store in an air-tight container in the fridge for up to 1 week, or in the freezer for up to 2 months.