Grease a large skillet with oil and heat up over medium-high heat. Add spinach and give it a good stir. Cook for five minutes over medium heat, stirring occasionally. Now add tomatoes, bell peppers, and broccoli. Continue to cook for 3-4 minutes.
In a small bowl, whisk together eggs, cheddar, and ricotta. Add into a frying pan and cook for 2 more minutes. Finally, crack the remaining three eggs. Remove from the frying pan and transfer to the oven.
Bake for 5 minutes, or until eggs are completely set. Remove from the oven and sprinkle with chopped celery leaves.