Cheesy layered chicken and vegetable roast

Ingredients

• 1 small red onion
• 1 large bell pepper , preferably red, yellow or orange
• 2 skinless, boneless chicken breasts
• 1/4 cup kalamata olives , pitted, or pimento-stuffed olives
• 2 tbsp olive oil
• 1/2 tsp dried oregano leaves
• 1/4 tsp paprika
• 1/4 tsp salt
• 1/4 tsp pepper
• 1 cup grated mozzarella , or cheddar cheese