Preheat oven to 375 and line a rimmed baking sheet with parchment paper.
In a large bowl, mix together chicken, pesto, salt, and pepper until chicken is thoroughly coated.
Place chicken breasts on prepared baking sheet. Spread extra pesto left in the bowl on each piece.
Bake for 30 minutes, or until chicken is fully cooked.
Traditional pesto usually has Parmesan cheese. To make this paleo/whole30/dairy free, make sure you use a pesto with no cheese.
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.