Heat 1 tablespoon olive oil in a medium sauté pan over medium heat, add the diced shallot and cook 2–3 minutes until translucent, add the spinach with a pinch of salt and wilt for about 2 minutes; transfer to a bowl and press or squeeze to remove excess liquid until you have about 1/3 cup packed spinach.

In a large bowl combine the ground turkey, drained spinach, panko, egg, Greek yogurt, 3 tablespoons Parmesan, 1 clove minced garlic, salt, pepper, and oregano; mix gently until just combined and form into sixteen 1.5-ounce meatballs.

Preheat oven to 375°F and heat 1 tablespoon olive oil in a 12-inch skillet over medium-high; sear half the meatballs until golden on most sides (about 3–4 minutes), transfer to a rimmed baking sheet, sear the remainder, then bake the sheet for 10–12 minutes until internal temperature reaches 165°F; rest meatballs 5 minutes.

Return the sauté pan to medium heat, add butter, sauté 1 minced garlic clove 30 seconds, stir in the flour and cook 1 minute, whisk in half-and-half and chicken broth and simmer until slightly thickened (3–4 minutes), stir in the reserved spinach, Dijon, remaining Parmesan, season to taste and simmer 1–2 minutes.

Add rested meatballs to the sauce, warm 1–2 minutes while spooning sauce over them, finish with lemon juice and chopped parsley, and serve hot.