Preheat oven to 350 degrees F.
Mash chickpeas with potato masher or in food processor. Add onions and garlic and blend. Add parsley, flour, coriander, cumin, baking powder, salt, and pepper and mix into a thick paste consistency.
Line baking sheet with parchment paper and spray with olive oil spray. Shape falafel into balls (size of golf balls) and place on baking sheet. Bake 20 minutes, turning halfway.
Mix yogurt with zest and juice. Taste and season with salt accordingly. Serve falafel with yogurt dip.