Place the low-fat cottage cheese and non-fat plain Greek yogurt into a high-speed blender. Blend until completely smooth and the cottage cheese no longer has a chalky texture, approximately 5 minutes.
For safety, remove the blender blade. Add the prepared spinach, Knorr Vegetable Recipe Mix, finely chopped water chestnuts, chopped green onions, garlic powder, salt, and freshly ground black pepper directly to the blended cottage cheese mixture.
Using a rubber spatula, thoroughly fold and stir the ingredients together until they are evenly distributed. Transfer the finished mixture from the blender container into a large bowl.
Cover the bowl securely with a lid or plastic wrap. Refrigerate the spinach dip for a minimum of 2 hours so the flavors have sufficient time to blend.
Once thoroughly chilled, taste the dip and add extra salt, black pepper, or garlic powder as necessary. Serve cold with preferred chips, crackers, or fresh vegetables.