Preheat oven to 350 degrees. Line a mini muffin tin with 20 paper liners.
Add applesauce, pumpkin, eggs, spinach, oil, and maple syrup to a blender. Blend until smooth.
Add remaining ingredients besides the chocolate chips. Blend until all ingredients are well combined and oats are finely ground. Scrape down the sides with a spatula to make sure nothing is stuck.
Scoop or spoon batter into the paper liners, filling each one to the top. Add mini chocolate chips to the top of each muffin, if using.
Bake until cooked through and a toothpick inserted into the center comes out clean, about 12 minutes. Once cool enough to handle, remove muffins to a cooling rack and cool completely. Store in a container at room temperature for 2 days or in the fridge for 4 to 5 days. Wrap and freeze for up to a month.