Cut the baked potatoes in half and scoop out the potato flesh.
Put the sundried tomatoes, basil, tomato purée and garlic into a small food processor and whiz until you get a rough paste (add a drop of oil to it from the jar if it’s too dry).
Mix a spoonful of this paste with the potato flesh.
Drain, then slice the mozzarella.
Spoon some of this paste into the potato skins, then add a spoonful of the potato mixture. Cover with a slice of mozzarella then bake for about 20 minutes, until the cheese has melted and browned.