Add milk along with baby spinach into the blender.
Add the remaining ingredients - banana, strawberries, and date.
Blend until smooth.
Serve immediately for the best tasting smoothie.
Notes
Variations
You can skip the strawberries to make spinach banana smoothie.
You can use yogurt too instead of milk.
Replace dates with honey or maple syrup.
You can throw in a few ice cubes too but I prefer my smoothies as close to room temperature as possible (especially during the winter).
If you don't mind a bit of crunch in your smoothie, serve it with granola.
Tips
Don't toss those overripe bananas. Peel and chop them and put them in the freezer. Use it in this smoothie without thawing.
Use a high-performance blender like Blendtec or Vitamix for best results.
Use baby spinach because it is milder and sweeter than mature spinach.
I use 1 cup of spinach for two servings. You can always start with one cup and add more greens as you get acclimated to the taste of spinach in your smoothie.
You can prep ahead for this smoothie - add all the ingredients except milk and dates in a glass jar and freeze it. Remove it from the freezer just before making the smoothie, add milk and dates and blend.