Preheat the oven to 350° F.

Spray a 9x13-inch baking dish with nonstick cooking spray.

Finely mince the scallion. Roughly chop the artichokes.

Set a large skillet over medium heat and add the olive oil. Once shimmering, add spinach to the pan. Cook, stirring frequently with a rubber spatula, until the the spinach is wilted, 1-2 minutes. Add the artichokes and cook for a minute longer. Remove from the heat.

In a large mixing bowl, whisk together the eggs, scallion, sour cream, garlic powder, salt, and black pepper. Add the spinach and artichokes and shredded cheese. Fold with a rubber spatula until the vegetables and cheeses are evenly distributed.

Pour the mixture into the prepared baking dish.

Bake the casserole on middle rack of oven until it is golden brown on top and a toothpick inserted in the center comes out clean, 40-45 minutes.

Check to see that casserole is done. Remove from oven or add time as needed.

Allow the casserole to cool for at least 10 minutes before serving.

Cut the casserole into squares, or simply spoon onto plates. Serve.