Preheat oven to 400 ̊F. Lightly grease a 12-slot muffin pan.
Divide onion, bell pepper, cooked ham, and Cheddar cheese evenly into each slot.
In a medium sized bowl whisk eggs, half and half cream, salt and pepper. Pour over filling into each slot until almost full. Top with mozzarella cheese.
Bake for 20-25 minutes or until a dark golden rim starts to form. Once ready, remove from pan, garnish with green onions and serve.