My Grandmother's Easy Chicken Frittata

Ingredients

• 6 large eggs (approx. 240 ml)
• 1 cup cooked chicken, shredded or diced (approx. 150 g)
• 1 cup baby spinach, chopped (approx. 30 g)
• 1 bell pepper, diced (approx. 150 g)
• 1 small onion, diced (approx. 100 g)
• 1/2 cup shredded cheese (Cheddar or mozzarella) (approx. 60 g)
• 1 tablespoon olive oil (approx. 15 ml)
• Salt, to taste
• Black pepper, to taste
• Fresh herbs (such as parsley or basil), for garnish