In a large skillet, heat olive oil over medium heat and add diced onion. Sauté till onions are soft, about 5 minutes. Reduce heat to medium low, add the chopped tomatoes and continue to sauté for an additional 5 minutes. Add broth, salt, and pepper and bring to a simmer. Simmer for 15 minutes and then add cream and pesto and stir till combined. Blend the soup in a blender, ½ at a time to not overflow the blender. Return the soup to the pot and stir together. Serve hot.