Prep the pan and oven: Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly grease with oil.
Blend the greens and wet ingredients: In a blender, add bananas, spinach, eggs, applesauce, oil, vanilla, and maple syrup or honey (if using).
Blend until completely smooth and bright green.
Whisk the dry ingredients: In a large bowl, whisk flour, baking powder, baking soda, cinnamon, and salt. Stir in ground flaxseed if using.
Combine gently: Pour the blended mixture into the dry ingredients. Stir with a spatula until just combined.
Don’t overmix. Fold in raisins or mini chips if using.
Fill the cups: Divide the batter evenly among the muffin cups, filling each about 3/4 full.
Bake: Bake for 14–18 minutes, or until the tops spring back when touched and a toothpick comes out clean or with a few moist crumbs.
Cool: Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. This helps them set and keeps the texture soft.
Serve: For toddlers, you can halve or quarter the muffins.
Pair with yogurt, nut butter, or a little fruit for a balanced snack.