Preheat your oven to 180C (350F). Grease a 20cm (8in) oven proof frying pan or springform pan. Mix eggs, spinach and feta in a medium bowl until just combined and pour into your prepared pan. No need to season as the feta adds plenty of salt.

Bake for 15-20 minutes or until frittata is puffy and just cooked through.

Divide between two plates and drizzle with chilli oil (if using).