01 - Warm olive oil in a large heavy-bottomed saucepan or Dutch oven set over medium heat. Add the chopped onion and sauté for approximately 3 minutes, stirring occasionally, until translucent and softened.
02 - Add the minced garlic, diced red bell pepper, carrot, and celery to the pot. Continue cooking for 5 to 6 minutes, stirring frequently, until the vegetables have begun to soften and release their natural sweetness.
03 - Sprinkle in the smoked paprika, sweet paprika, and red pepper flakes. Stir continuously for about 1 minute to toast the spices and draw out their full aromatic depth.
04 - Pour in the canned diced tomatoes with their juices. Cook for 3 to 4 minutes, stirring occasionally, allowing the tomatoes to reduce slightly and meld with the spiced vegetable base.
05 - Add the vegetable broth and drop in the bay leaf. Raise the heat to bring the mixture to a gentle boil, then immediately reduce to low heat. Cover partially and let simmer for 20 minutes so the flavors develop and the broth thickens.
06 - Gently fold the drained butter beans into the stew, taking care not to crush them. Continue simmering uncovered for another 10 minutes, allowing the beans to absorb the surrounding flavors and the liquid to reduce to a rich consistency.
07 - If using spinach, stir it in during the final 2 minutes of cooking. Toss gently until the leaves are just wilted and bright green.
08 - Taste the stew and adjust the salt and pepper as needed. Remove and discard the bay leaf. Ladle into warm bowls, finish with a scattering of fresh parsley and a thin drizzle of extra virgin olive oil, and serve immediately.