Heat the olive oil in a large pan over medium heat. Add the diced onion and cook for 5 minutes until soft.
Add the garlic and red pepper, cook for another 3 minutes until the pepper starts to soften.
Stir in the smoked paprika and oregano, cook for 30 seconds until fragrant.
Pour in the chopped tomatoes, butter beans, stock cube and water. Stir well and bring to a simmer.
Cover and simmer for 15 minutes, stirring occasionally, until the sauce has thickened.
Stir through the spinach until wilted, season with salt and pepper, and serve hot.