Fry half the garlic in a tbsp olive oil. Add the tinned tomatoes and chilli flakes and simmer for 10 minutes until thickened. Stir in the basil.
Cut the ends off the courgettes and discard. Using a potato peeler, cut neat strips of courgette to use as the ‘lasagne’, stopping when you hit the spongy centre part. Roughly grate the remaining courgette middles and any offcuts.
Heat 1 tbsp olive oil in a pan. Cook the grated courgette, rest of the garlic and another pinch of chilli flakes until soft. Add the ricotta, mascarpone and 2 tbsp of parmesan, season and mix well.
Oil a small baking dish. Line with a layer of courgette slices. Top with a layer of ricotta. Add a quarter of the tomato sauce then cover with another layer of courgette strips. Repeat twice, ending with courgette strips. Brush with oil and sprinkle over the last of the parmesan. Bake for 20-30 minutes until bubbling.