Heat olive oil in a large skillet over medium heat. Add the diced onion and cook until tender, about 5 minutes. Stir in the minced garlic until fragrant, about 1 minute.
Add the tomato paste and red pepper flakes, cooking until slightly darkened, around 1 minute. Then, pour in the broth, diced tomatoes, white beans, olives, and capers. Simmer over low heat until thickened, about 10-15 minutes, stirring occasionally.
Remove the skillet from heat and stir in the parsley, lemon juice, and parmesan cheese. Taste and adjust seasoning if needed, considering the saltiness from olives, capers, and cheese.
Serve the White Bean Puttanesca as is, with garlic bread, or spooned over polenta for a heartier meal.
Notes
For a vegan option, use plant-based parmesan cheese.