Step 1: Pat the short ribs dry with paper towels and season generously with salt and pepper.
Step 2: Heat olive oil in a large Dutch oven or oven-safe pot over medium-high heat. Sear the short ribs on all sides until deeply browned, about 3-5 minutes per side. Remove ribs from the pot and set aside.
Step 3: Add chopped onion, carrots, and celery to the pot. Sauté for 5-7 minutes, until softened, scraping up any browned bits from the bottom of the pot. Add minced garlic and cook for another minute until fragrant.
Step 4: Pour in the red wine, scraping the bottom of the pot to deglaze. Bring to a simmer and cook until the wine has reduced by about half, about 5 minutes.
Step 5: Stir in the beef broth, diced tomatoes (with their juice), rosemary sprigs, thyme sprigs, and bay leaves. Return the seared short ribs to the pot, ensuring they are mostly submerged in the liquid. Bring the liquid to a gentle simmer.
Step 6: Cover the Dutch oven tightly with a lid and transfer to a preheated oven at 325°F (160°C). Braise for 2.5 to 3 hours, or until the short ribs are fork-tender and easily pull away from the bone.
Step 7: Carefully remove the pot from the oven. Remove the short ribs and set aside. Skim off any excess fat from the surface of the braising liquid. Remove and discard the herb sprigs and bay leaves.
Step 8: Return the pot to the stovetop over medium heat. Stir in the rinsed and drained butter beans. Bring to a simmer and cook for 5-10 minutes, allowing the beans to warm through and absorb some of the sauce.
Step 9: Return the short ribs to the pot. Add the fresh spinach, stirring gently until it wilts, which should only take 1-2 minutes. Taste and adjust seasoning with salt and pepper if needed.
Step 10: Serve hot, garnished with fresh chopped parsley.