Preheat the oven to 400F. Then take a sharp knife and slice the chicken breasts lengthways down the center of the breast, so that you can open it up like a butterfly. This is a great way to make it thin.
Place the chicken into a bowl with olive oil, smoked paprika, oregano, salt, pepper, garlic, lemon juice, and thyme leaves. Toss it with two spoons to coat the chicken all over.
Toss the sliced red onion into a baking dish and then lay in the chicken breasts along with the tomatoes and olives scattered on top.
Cover the dish tightly with foil and then bake for 10 minutes covered and then 8 minutes with the foil off. Remember that your chicken might be slightly thinner or thicker as well as your oven running a little hotter or colder. So watch the chicken so that you don’t overcook it.