01 -
Preheat the oven to 400°F (205°C) and grease a 9x13-inch casserole dish.
02 -
Heat the olive oil in a skillet over medium heat. Add the baby spinach, diced zucchini, and diced yellow squash. Cook until the spinach wilts and the squash softens. Drain any excess liquid.
03 -
In a large mixing bowl, combine the cooked vegetables with the feta cheese, parmesan cheese, breadcrumbs, egg whites, salt, garlic powder, ground black pepper, and dried basil. Stir well until everything is evenly combined.
04 -
Spread the mixture evenly in the prepared casserole dish.
05 -
Bake in the preheated oven for 30-40 minutes, or until the top is golden brown.
06 -
Let the casserole cool slightly before serving.