Prepare the ingredients by chopping spinach, sun-dried tomatoes, and olives. Crumble the feta cheese and set aside.

Heat olive oil in a non-stick skillet over medium heat until shimmering.

Crack the eggs into a bowl, season with salt and pepper, and whisk until well combined.

Pour the egg mixture into the skillet, let sit undisturbed for 30 seconds, then stir gently for 2-3 minutes until creamy.

Fold in the spinach, sun-dried tomatoes, and olives, cooking for another 2-3 minutes until well-combined.

Remove from heat and gently fold in the crumbled feta cheese.

Toast the bread until golden brown and crispy.

Assemble the sandwich by placing the egg mixture on one slice of toasted bread and topping with the second slice.

Garnish with fresh basil leaves if desired, cut in half, and serve immediately.