Preheat the oven to 375°F and grease a medium casserole dish with one teaspoon of olive oil.
Add the chopped spinach, red bell pepper, and scallions to the bottom of the prepared casserole dish. Season with salt and pepper to taste and set aside.
In a medium bowl, whisk the eggs with milk and fresh parsley until smooth and slightly frothy. Season to taste with salt and pepper.
Pour the egg mixture on top of the vegetables and crumble the feta cheese on top. Place the cherry tomatoes on top and bake until golden-brown and set, about 25-30 minutes.
Allow casserole to cool for a few minutes before slicing and serving.