Preheat your oven to 375 degrees. Grease a baking dish lightly with olive oil.

In a very large pan or wok (I use a wok), heat 2 1/2 tablespoons of olive oil over medium heat. Add the onion and sauté for about 3 minutes. Add the garlic and continue to cook for one minute. Add the spinach toss as you cook it down for about 4 to 5 minutes.

Place a heat resistant colander in the sink, and transfer the spinach into the colander to allow it to drain a bit.

Place the remaining 1/2 tablespoon of olive oil into the empty wok or pan. Add the flour and stir it into the oil. It will be a bit thick. Cook for a minute, then add the almond milk and whisk until you get a smooth texture. Simmer until the sauce thickens, about 3 minutes. Return the spinach to the pan and mix until combined. Add half of the feta cheese, if using, and mix.

Pour the spinach mixture into the prepared pan. In a small bowl, combine the panko with the remaining olive oil. With your fingers, just work the oil into the panko to combine, then add in the remaining feta cheese. Sprinkle over top of the spinach.

Bake for 15 to 20 minutes.