Grease a small 3-cup casserole dish or ovenproof skillet with nonstick spray.
Heat 1/2 tablespoon olive oil in a nonstick skillet over medium high heat. Add the onions and sauté for 5 minutes or until soft and fragrant.
Add the turkey, chili powder, salt (optional) and onion powder. Brown the meat until fully cooked and crumbled. Transfer to a bowl and set aside.
Add the remaining 1 tablespoon olive oil and reduce the heat to medium low. Add the garlic and sage and sauté for 2-3 minutes.
Add the spinach and stir until wilted, about 2 minutes. Transfer to a bowl and set aside.
In a mixing bowl, whisk the eggs and 1/3 cup milk. Add the cooked turkey, spinach, potatoes, and Mozzarella cheese. Stir until combined. Transfer to the casserole dish. Top with the Parmesan cheese.
Bake for 20-25 minutes or until the top is golden brown and the casserole springs back when touched.
Serve with remaining 8-ounce glass of milk.
340 calories; 14 g fat; 4 g saturated fat; 140 mg cholesterol; 32 g protein; 23 g carbohydrates; 2 g fiber; 430 mg sodium; 515 mg calcium (50% of daily value). Nutrition figures based on using fat free milk, and include an 8-ounce glass of milk.