Preheat the oven to 190°C.
Cut the courgette into thin slices (vertically), then cut in half. Do the same with the frankfurters.
Put a layer of courgette in the bottom of a small baking dish.
Mix the garlic with the oil and one pinch of salt.
Brush the courgette slices with the garlic oil. Add a layer of the frankfurters then spoon over half of the soured cream and spread it pout evenly. Season with pepper.
Repeat, then cover the top with sliced mozzarella or grated cheese.
Bake in the oven for about 30-35 minutes, until the top is golden and the courgette has cooked through.
Serve warm.