1. 1. Preheat the oven to 350°F (180°C).

2. 2. In a skillet, sauté diced white onion, chopped fresh tomatoes, and sliced celery until softened.

3. 3. In a mixing bowl, beat the eggs and stir in the sautéed vegetables.

4. 4. Grease a muffin tin and pour the egg mixture into each cup.

5. 5. Tear pieces of prosciutto and place them on top of each egg muffin.

6. 6. Sprinkle shredded mozzarella cheese over the prosciutto.

7. 7. Bake in the preheated oven for 20-25 minutes, or until the eggs are set and the cheese is melted and bubbly.

8. 8. Remove from the oven and let cool slightly before serving.