Preheat oven to 375°F (190°C). Grease a 9×13-inch baking dish.

If using frozen spinach, thaw and squeeze dry. For fresh, chop and sauté until wilted, then cool.

In a skillet, heat olive oil. Sauté onion until soft, then add garlic for 1 minute. Remove from heat.

In a large bowl, whisk eggs. Stir in feta, cottage or ricotta, spinach, onions, garlic, salt, and pepper.

Pour mixture into baking dish. Spread evenly.

Bake for 35-40 minutes or until set and golden on top.

Let cool for 10 minutes before slicing and serving.