In a small sauce pan sauté the chopped onion with 1/2 Tbsp olive oil, until beginning to soften. Add garlic & cook 30 seconds more. Add spinach & cook a minute or so more.
(** Note .. at this point, for a bit of added flavor, it's nice to add a small splash of wine & let the mix reduce a minute or two more)
Add all of the ingredients (minus the turkey) to your food processor & pulse two or three times
In a large bowl, using your hands or a fork, gently mix with the ground turkey until just combined.
Cover and chill in the refrigerator for at least an hour
Using your hands, shape the meatballs into rounds, and place the meatballs in individual, miniature muffin tin cups (you should have about 20)
Bake for 18-20 minutes or until golden and cooked through. (For an added bit of crisp & brownness .. they can be placed under the broiler for a few seconds)