Preheat the oven to 400°F.
In a large ovenproof skillet, cook the bacon until the fat has rendered and it starts to crisp up. Remove the bacon and set aside.
Add the olive oil to the skillet. Season the chicken thighs on both sides with salt and pepper.
Place the chicken thighs skin-side-down in the skillet and cook until the skin is browned and crispy, about 6-8 minutes. Flip the chicken over and cook for another 5 minutes. Remove the chicken from the skillet and set aside.
Add the garlic to the skillet and cook for about 1 minute until fragrant. Add the capers and red chile flakes and cook for another minute.
Add the canned plum tomatoes and cherry tomatoes to the skillet. Use a wooden spoon to break up the whole tomatoes. Season with salt and pepper and add the oregano if using.
Return the chicken to the skillet, nestling it into the tomato mixture. Top each piece of chicken with a slice of mozzarella.
Transfer the skillet to the oven and bake for about 10-15 minutes, or until the chicken is cooked through and the cheese is melted and bubbly.
Remove from the oven and sprinkle with chopped basil. Serve hot.
