You can use any kind of apple in this recipe. It will taste best if your apples taste sweet. There's a big range of flavors in apples, so just know the final flavor of the smoothie depends on the flavor of the apples. Honeycrisp and Pink Lady are good options.
Start on low and work up to high, blending very smooth. If the mixture seems too thick, add a little milk.
Add a pinch of cinnamon and maple syrup if using.
Serve or store for later and serve within 24 hours.
Notes
You can store this smoothie in an airtight container or pouch in the refrigerator for up to 24 hours.
I prefer the consistency and flavor of this smoothie made using steamed and cooled apples. This ensures that they blend all the way to creamy. To steam apples: Dice apples and place into a steamer basket set over a pot with 1 inch of water. Cover and steam apples until soft. You can also just simmer diced apples in a little water until soft.
If you have a very strong blender, like a Vitamix, you can use fresh or frozen apples in this recipe.
If you use fresh apples, add a few ice cubes to make it smoothie consistency.
Using Greek yogurt will add more protein and creaminess to the smoothie, though it's good with milk too!