Heat the oven to 375°F. Line a rimmed baking sheet with parchment paper. In a small bowl, combine the spinach and feta for the filling.

In a large bowl, mix the ground turkey, egg, breadcrumbs, milk, garlic powder, oregano, salt, and black pepper until just combined. Avoid overmixing so the meatloaf stays tender.

Pat the turkey mixture into a rectangle about ½ inch thick on the prepared baking sheet. Spoon the spinach and feta mixture down the center, leaving a border around the edges. Fold the turkey over the filling and pinch the seams and ends closed. Shape it into a loaf with the seam underneath.

Bake until the center reaches 165°F, about 45 to 55 minutes. Let the meatloaf rest for 10 minutes before slicing so the filling stays in place.

While the meatloaf rests, bring the chicken broth and olive oil to a boil in a small saucepan. Stir in the couscous, cover the pan, and remove it from the heat. Let it stand for 5 minutes, then fluff with a fork and stir in the lemon zest and lemon juice.

Slice the meatloaf and serve it with the lemon couscous.