Place the sliced banana, fresh spinach, protein powder, Greek yogurt, milk, almond butter (or peanut butter), chia seeds, and optional honey (or maple syrup) into a blender.
Add a few ice cubes to the blender to make the smoothie cold and refreshing.
Blend on high speed until all the ingredients are well combined and the smoothie is smooth and creamy.
Stop the blender and scrape down the sides if needed, then blend again briefly.
Taste the smoothie and adjust sweetness if necessary by adding more honey or maple syrup.
Once the desired consistency and sweetness are achieved, pour the smoothie into glasses.