Heat the oil in a frying pan and cook the bacon on a high heat until browned and crispy. Remove from the pan, discard all but 1 tbsp of fat from the pan and add in the spinach. Allow to wilt for 1-2 minutes (doesn't need to be on the hob), then remove from the pan. Chop both the bacon and spinach into small pieces.
Take the part baked rolls out of the packaging and place on a chopping board. Using a sharp knife, carefully cut out an oblong hole from the top of the rolls. Scoop out the bread, ensuring you don’t pierce the bottom of the rolls. Place the rolls on a baking tray. Discard the scooped out bread.
Mix together the cream cheese, mayonnaise and garlic in a bowl. Stir in the mozzarella and half the cheddar along with the black pepper, bacon and spinach. Spoon the mixture into the bread rolls and top with the remaining cheese.
Place in the oven and cook for 10 minutes – until the bread and cheese is golden brown.
Remove from the oven and sprinkle with fresh parsley before serving.