Core the apples and chop them into 2 cm / 3/4-inch chunks, leaving the peel on. Pull the mint leaves off the stems and squeeze the lemon.
Add the ingredients to the blender jar in this order: almond milk, lemon juice, chlorella powder, mint, apple, frozen banana, then ice. Liquid first keeps the powder from clumping.
Blend on low for 10 seconds, then on high for 50 to 60 seconds until the color is an even pale green with no flecks of apple skin. If it's too thick, add 2 tbsp more almond milk and blend for 10 seconds.
Taste and add a few extra banana chunks if it's too tart. Pour into two 350 ml glasses and drink within 15 minutes.