01 -
Set the oven to 175°C and allow it to preheat while you prepare the vegetables.
02 -
Warm olive oil in an oven-safe skillet over medium heat. Add the diced onion and cook for 2-3 minutes until translucent.
03 -
Stir in the diced bell peppers and zucchini. Sauté for approximately 5 minutes until the vegetables are softened.
04 -
Fold in the spinach or kale until wilted. Season generously with salt and black pepper.
05 -
In a separate bowl, vigorously whisk the eggs, then pour them evenly over the vegetables in the skillet.
06 -
Gently distribute the crumbled feta over the surface of the egg mixture.
07 -
Place the skillet in the preheated oven. Bake for 20–25 minutes until the frittata is set in the centre and lightly golden around the edges.