Place the frozen strawberries and ¼ cup of milk into the blender and process for about 1 minute until the strawberries are completely broken down.
Pour into one serving glass. Don't get any on the sides!
Rinse out the blender. Make sure you get rid of all those tiny strawberry seeds.
Place the frozen mango, ½ cup of milk and 1 tablespoon of agave nectar into the blender and process for another minute until the mango has totally broken down.
Gently pour the mango smoothie on top of the strawberry smoothie. Again - make sure you don't get any on the sides!
Serve immediately or cover and store in the fridge for up to two days.
Notes
If you don't think your smoothie is thick enough to create a firm layer, scoop it back into the blender and blend with more fruit to thicken it up.