Add the tomatoes and olive oil to a small baking dish (just large enough to hold everything) and stir to combine.
Place the chicken breasts in the center of the tomatoes and brush over the pesto.
Cover the baking dish with a lid or aluminum foil and bake for 20 minutes, or until the chicken reaches an internal temperature of 150 Fahrenheit.
Remove the lid and stir the tomatoes gently.
Place the sliced mozzarella on top of the chicken and then place it back in the oven for an additional 15 minutes, or until the internal temperature of the chicken reaches 165 degres Fahrenheit.
If you like the cheese to get those delicious browned spots, turn the broiler to high for 1 to 2 minutes, but keep your eye on it so it doesn't burn.
Garnish with fresh basil.
Notes
Storing: Store basil pesto chicken in an airtight container in the fridge for up to 3-4 days before reheating and serving. Freezing: You can freeze this chicken by adding it to an airtight container or freezer-safe bag with the air removed for up to 3 months. Thaw in the fridge overnight before reheating & serving.