Preheat oven to 425℉. Pat chicken pieces very dry with a paper towel.
Heat a heavy, oven safe large skillet over medium high heat, add a drizzle of olive to coat the bottom of the pan.
Add the zucchini, yellow squash, and onion. Saute until onions are translucent, squash is tender, and they have started to brown, about 5-8 minutes. Remove to a bowl and set aside.
Add another drizzle of olive oil, followed by the chicken. Season chicken with a sprinkle of salt. Saute chicken, flipping occasionally, until golden brown on all sides and almost cooked through, about 5-8 minutes.
Reduce heat to medium, add a drizzle of olive oil if needed, followed by the garlic. Saute until garlic is translucent, about 1 minute. Add in the canned tomatoes, Italian seasoning, pesto, and a generous pinch of salt and pepper.
Using the back of a spoon or a potato masher, start breaking up the tomatoes until they integrate into the sauce. Simmer sauce for 15 to 20 minutes until reduced and thickened.