In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add the diced onion and scallions, sautéing until they are translucent and fragrant, about 5 minutes.
Add the fresh baby spinach to the skillet in batches, stirring until it wilts down completely. This may take about 5-7 minutes. Once wilted, remove from heat and let it cool slightly.
In a large mixing bowl, combine the cooked spinach mixture, ricotta cheese, feta cheese, chopped dill, eggs, and salt. Mix everything together until well combined and set aside.
Preheat your oven to 375°F (190°C). Lay out one sheet of phyllo dough on a clean surface and brush it lightly with olive oil. Repeat this process with 4-5 more sheets, stacking them on top of each other.
Once you have your layers of phyllo dough, spoon a portion of the filling along one edge of the dough. Fold the sides of the dough inwards and roll it up tightly, forming a log. Place the rolled Spanakopita seam-side down in your greased baking dish. Repeat this process with the remaining phyllo sheets and filling, arranging the rolled pieces closely together in the baking dish.
Once all of your Spanakopita pieces are in the dish, brush the tops generously with more olive oil. Using a sharp knife, score the top of the pie into squares or diamond shapes, allowing steam to escape during baking.
Bake in the preheated oven for 30-40 minutes, or until the tops are golden brown and crispy.
Remove from the oven and let it cool for a few minutes before serving. Enjoy warm or at room temperature.