Preheat the oven to 180C/350F. Season the chicken breasts with salt and pepper and brown in olive oil in a pan until golden but not cooked all the way through. This will take 2-3 minutes per side at medium-high heat.
To a large baking dish (or the same pan you used the chicken if oven proof) add the cherry tomatoes, minced garlic and 2 tbsp of the olive oil, mix to coat the tomatoes, place the chicken directly on the tomatoes and spread the basil pesto on the chicken, cook in the oven for 10 minutes.
Take out of the oven and turn the oven temperature up to 200C/400F and top the chicken with sliced mozzarella, cook for 10-12 minutes longer until the mozzarella is melted, the chicken is fully cooked and the tomatoes are blistered.
{Optional serving suggestion} Remove the chicken from the pan, then roughly crush the tomatoes with a potato masher and stir the sliced fresh basil and capers into the tomatoes. Serve with pasta.