Chicken and Butternut Gnocchi

olive oil, divided

skinless, boneless chicken thighs, cut into 1-in. pieces

(1/2-in.) cubed peeled butternut squash

chopped yellow onion

pkg. whole-wheat gnocchi

unsalted chicken stock (such as Swanson)

prepared refrigerated pesto

chopped fresh sage

chopped garlic

baby spinach, chopped

Parmesan cheese, grated (about 1/4 cup)