Cook the bacon in a saucepan with the oil for 3-4 minutes until golden over medium heat. Add the onion, garlic, thyme and continue to cook until the onion is soft. Then add tomato and tomato paste, simmer for 10 minutes until reduced. Add the beans and cook for 2 minutes to warm through. Let cool.
Heat the toasted sandwich maker. Butter slices of bread. Place bread on the toastie maker, butter side down, top with cheddar cheese, bean mixture and mozzarella. Place another slice of bread, butter side up, then close the lid to make a toastie.