"This classic soup is perfect for busy weeknight dinners...."
olive oil
medium yellow onion, chopped
cloves garlic, minced
(14-oz.) can fire-roasted crushed tomatoes
chicken stock
(9-ounce) package fresh cheese tortellini
(5-ounce) package fresh baby spinach
rotisserie chicken, shredded (about 10 ounces)
to 1 teaspoon crushed red pepper
fresh lemon juice
Grated Parmesan, torn basil leaves, and pesto, for serving