Line the air fryer basket with parchment paper and lightly spray or brush it with cooking oil.
Add the well‑drained cooked peas to the lined basket and spread them into an even layer.
Scatter the finely chopped red onion and chopped sun‑dried tomatoes over the peas.
Crack the four eggs into the basket, then add the grated Parmesan or Grana Padano, salt and black pepper.
Gently mix everything together directly in the basket until evenly combined.
Air fry at 180°C / 356°F for about 10 minutes, or until the eggs are mostly set.
Sprinkle the shredded low‑moisture mozzarella evenly over the top.
Air fry for another 3 minutes, or until the cheese is melted and lightly golden.
Let the bake cool for 2–3 minutes, then lift it out using the parchment, slice and serve warm.