Preheat your oven to 180°C (350°F) and line your muffin tin with paper liners. Or grease the pan if you’re out of liners. I’ve done that more times than I can count.
In a blender, combine the mashed bananas, eggs, spinach, oil, and vanilla. Yep, all of it. Don’t panic about the spinach. It blends into a smooth green mix that you won’t even see or taste later. It’s our little secret.
In a big bowl, mix the sugar, flour, cocoa powder, baking soda, and salt. Just a quick whisk or fork stir to get the dry stuff evenly combined.
Pour the spinach-banana blend into your dry ingredients. Stir gently until it’s just mixed. It’ll be thick, but that’s okay. Try not to overmix or your muffins might turn out dense.
Fold in the chocolate chips. I always “accidentally” add a little extra. Who can resist? Especially if you're saving one for yourself with your coffee later.
Scoop the batter into your muffin tin, filling each cup about ¾ full. An ice cream scoop makes it super easy (and less messy).
Bake for 18 to 22 minutes. Check with a toothpick. If it comes out clean (melty chocolate is okay), they’re ready.
Let them cool... or not. Honestly, my favorite way to eat them is warm.