Bring a large pan of salted water to the boil.
Slice the courgette/zucchini into circles around 1 cm (0.4") thick.
Cut the garlic clove in half and place in a frying pan with the olive oil. Gently heat until lightly golden.
As soon as the garlic is lightly golden, remove from the pan and add the courgettes/zucchini. Take care as they can spit a bit. You may have to cook them in two batches, depending on size of your frying pan.
Whilst the courgette / zucchini cooks, place the spaghetti in the water and cook per packet instructions to al dente.
Turn the zucchini/courgette occasionally until medium brown and blistered. If you turn them too much they won't achieve this - and this adds flavour!
Once brown both sides, remove to kitchen paper towel on a plate to remove excess oil. (Cook the second batch if cooking in batches).
Season the cooked zucchini/courgette with a pinch of salt, and black pepper.
Drain the spaghetti, keeping 1 cup/ 240ml of the cooking water. .
Tip the cooked pasta into the frying pan you cooked the zucchini/courgette in.
Add half of the cooked zucchini/courgette to the pan and sprinkle over the grated parmesan, and grated pecorino romano. Add half the torn basil leaves and a couple of spoonfuls of the cooking water.
Heat over a very gentle heat, stirring, until the cheese has melted. Add a little more pasta water if it's getting too dry - the sauce should be creamy. Stir through the rest of the cooked courgette / zucchini slices.
Transfer to serving plates and sprinkle over a little more grated parmesan and the rest of the torn basil, to serve.