Add pitted dates to hot water and let them hydrate for 30 min while you measure the other ingredients.
Preheat oven to 375F and prepare a muffin tray.
Discard the water from soaking the dates.
Add spinach, coconut oil, dates, Greek yogurt, bananas, eggs and oats to a high-powered blender and blend until smooth (scrape down the sides as needed, it may take several minutes).
Transfer the mixture to a bowl and add all purpose flour, mix until combined.
Add the baking powder and mix until incorporated (do not overmix).
Scoop the muffin batter into the muffin tray and bake for 20 minutes until a toothpick comes out clean and the muffins are golden on the edges.
Let them cool a bit and move to a wire rack.