Preheat the oven to 180°C.

Whisk the egg in a small bowl until well beaten, season with a pinch of salt and pepper.

Dice the avocado, and cherry tomatoes, and chop the spinach finely.

Lightly oil a muffin tin cavity with a drizzle of olive oil.

Pour the beaten egg into the prepared muffin tin cavity.

Add the diced avocado, cherry tomatoes, and spinach evenly on top of the egg mixture.

Sprinkle crumbled feta cheese on top.

Bake in the preheated oven for about 12-15 minutes or until the egg is set and fully cooked.

Remove from the oven and let cool slightly before serving.