Heat olive oil in a large pot over medium heat.
Add chopped onion. Cook for 5–6 minutes until soft and lightly golden.
Add garlic. Stir for 30 seconds until fragrant.
Stir in tomato paste and cook for 1 minute to deepen the flavor.
Pour in crushed tomatoes and vegetable broth. Stir well.
Add white beans, salt, pepper, and red pepper flakes.
Bring to a gentle simmer. Cook uncovered for 15 minutes.
Scoop out about 1 cup of the stew and blend until smooth.
Pour the blended mixture back into the pot and stir.
Add fresh basil and optional greens. Cook 2–3 more minutes.
Taste and adjust seasoning. Serve warm.