Add all the ingredients to a blender. Blend until smooth.
Notes
You can meal prep your strawberry banana peanut butter smoothies by placing all of the ingredients except the milk in a freezer bag, then dumping this into your blender and adding the milk then.
Alternatively, you can make the smoothies, then portion them into freezer bags and freeze them. Let them thaw overnight and enjoy in the morning, or blend with a little ice before enjoying.
If you have leftover smoothie, you can keep it in the fridge for up to a day. The smoothie will separate a bit, so give it a good stir before you finish it.