Preheat your Dutch oven over medium heat.
Add the olive oil to the Dutch oven and heat until shimmering.
Add the onion and cook until softened, about 5 minutes.
Add the garlic and cook for 1 minute more, until fragrant.
Stir in the crushed tomatoes, diced tomatoes, tomato paste, chicken broth, oregano, salt, and pepper.
Bring to a boil, then reduce heat and simmer, covered, for 1 hour, or until the flavors have melded.
Using an immersion blender or regular blender, purée the soup until smooth.
Garnish with fresh basil leaves, if desired.