Prepare your ingredients: Wash the spinach thoroughly. Peel the kiwis and banana if using, and slice them into smaller pieces for easier blending.
Add to blender: In a blender, combine the spinach, kiwi, banana (if using), and chia seeds.
Add liquid: Pour in the almond milk. You can adjust the amount based on how thick or thin you like your smoothie.
Blend: Blend on high until everything is completely smooth, scraping down the sides as needed. You can add ice cubes for a chilled smoothie.
Taste test: Before serving, taste your smoothie. If you prefer it sweeter, add honey or agave syrup and blend again.
Serve: Pour into a glass and enjoy immediately. You can also top it with some chia seeds or slices of kiwi for added visual appeal.