Preheat the oven to 350°F. In a large bowl, mix the oregano, red pepper flakes, garlic powder, salt, and nutmeg. Add the turkey and mix with a spatula or your hands.

Slick a large skillet with the olive oil and heat it over medium heat. Add the turkey mixture and cook until the meat is no longer pink, and a meat thermometer reads 165°F, about 7 minutes. Add the leeks and cook for another minute; then add the goat cheese. Keep cooking and stirring over low heat until the goat cheese just begins to melt.

Pour the turkey mixture into a 9 x 13-inch baking dish. Spread the spinach on top, and then pour in the egg whites. Use a spatula to make sure the egg whites are distributed evenly in the dish. .

Bake the casserole 35 minutes. Remove from oven and top with mexican cheese blend. Continue baking 10-15 more minutes or until a knife stuck into the center comes out clean.