Preheat the oven to 400°F (200°C).

In a bowl, whisk together the eggs (use 6 large eggs, or 8 large eggs if using a 12-inch skillet), almond milk, minced garlic, sea salt, and freshly ground black pepper until well combined.

Fold the chopped broccoli, chopped onion, and feta cheese into the egg mixture.

Grease an oven-safe skillet with extra-virgin olive oil and pour the mixture into the skillet, spreading it evenly.

Bake in the preheated oven for 15 to 20 minutes, or until the eggs are set — the top is lightly golden and the center is no longer jiggly.

Remove the frittata from the oven, let it cool for a few minutes, season to taste if needed, slice, and serve.