Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Drain and thoroughly rinse the chickpeas, then pat them dry with a paper towel to ensure maximum crispiness.
In a food processor, combine the chickpeas, liquid egg whites, parsley, cilantro, garlic, cumin, salt, and pepper.
Pulse the mixture until a coarse, uniform paste forms, being careful not to over-process into a puree.
Scoop the mixture and form into 6 even patties, placing them on the prepared baking sheet.
Bake for 20 to 25 minutes, flipping the patties halfway through, until the exteriors are golden-brown and firm.
While the falafel bakes, whisk together the Greek yogurt, tahini, and lemon juice in a small bowl until the sauce is smooth and creamy.
Arrange the fresh baby spinach on a plate, top with the warm falafel patties, and finish with a generous drizzle of the lemon-tahini sauce.