Preheat the oven and prepare the veg - Preheat the oven to 400℉, convection bake setting. Clean and chop the spinach and the arugula. Blanch in boiling water for 3 minutes, then pull out and rinse under cold water to stop the cooking. Drain and set aside. Chop the scallions (white and green parts). Chop the dill.
Make the filling - Break the eggs into a large bowl, and vigorously whisk them. Mix in the chopped scallions, mozzarella cheese, feta, and fresh dill. Fold in the blanched greens.
Prep and fill the baking dish(es) - Butter the bottom and sides of your baking dish(es) and dust with a light coating of bread crumbs. Pour the filling into the dish(es).
Make the topping; top the dish(es) - Combine the remainder of the bread crumbs and the the Parmesan cheese. Melt the butter and stir it into the breadcrumb mixture. Sprinkle it all over the top of the dish(es) and pat down. Cover with aluminum foil and, if you're using two ramekins, bake for 20 minutes (until set and puffed up); uncover and bake for 5-10 minutes longer, to brown the top. Alternatively, if you're using a single baking dish, cover and bake for 30 minutes, then uncover, and bake for 5-10 minutes longer.
Notes
I make my sourdough breadcrumbs from scratch. My method is described on the Methods and Pantry Notes page.