Preheat oven to 375°F (190°C).
In a large bowl, whisk together the eggs. Add spinach, onion, garlic and season with salt and pepper.
Pour mixture into an oiled baking dish or pie plate if desired for presentation purposes only.
Bake in preheated oven until set but still slightly jiggly around edges (about 15 minutes).
Remove from the oven and serve warm.