Heat the olive oil in a large pot over medium heat. Add the diced onion and cook for 5 minutes until it softens.
Stir in the minced garlic, curry powder, and ground ginger. Cook for 1 minute until the spices smell fragrant.
Add the butter beans, vegetable broth, and coconut milk. Bring the mixture to a gentle simmer and cook for 10 minutes, stirring occasionally.
Add the spinach a handful at a time, stirring until it wilts into the stew. Season with salt and black pepper to taste.
Serve the stew hot with lemon wedges on the side for squeezing over each bowl.