Pre-heat the grill /broiler.

Remove woody stems from the asparagus and chop spears into 4 portions.

Heat oil in a non stick cast iron pan and add in asparagus and onion and sauté for a few mins until soft.

Whilst vegetables are frying break eggs in a large bowl.

Remove thyme leaves for the sprigs and add these in to the eggs with the cream, salt and pepper and whisk very well and then add in the tomatoes and feta cheese and mix again.

When the asparagus and onion mixture is cooked pour the egg mixture into the frying pan and gently mix everything together and allow to cook on medium heat until the frittata starts to set.

Then transfer the cast iron pan to the grill and cook top of the frittata till it is set on top and slightly golden.