Preheat your oven to 350 F/180 C and line a casserole dish with baking paper. Crack the eggs in a large bowl and whisk until the yolks and whites are incorporated. Squeeze out as much liquid as you can from the spinach and add it to the eggs.
Step 2
Mince the garlic and thinly slice the onion and sundried tomatoes. Add them to the bowl—season with salt, pepper, dried parsley, and crushed red pepper.
Step 3
Add half the crumbled cheese, and whisk until all ingredients are distributed. Pour into the casserole and top with the remaining feta cheese. Transfer to the oven.
Step 4
Bake for 30-35 minutes until an inserted toothpick comes out clean, and the cheese is golden. Place the casserole dish on the counter and let it cool for a few minutes. Cut into 4 slices, garnish with fresh parsley, and serve.