Sprinkle the zuchinni slices with 1 1/2 tsp of salt and toss to coat.
Place the zucchini slices in a colander and leave them to sit and drain for 30-45 minutes.
Pat the slices dry thoroughly with a clean tea towel or paper towels.
Preheat the oven to 200 °C (or 180 °C fan-bake).
Place a deep saucepan over medium heat and add in the oil.
Once warm, add in the garlic and fresh thyme and allow them to sweat for 2 minutes.
Add in the flour and whisk it together. Fry the flour in the oil for 1-2 minutes.
Pour in the milk, add the nutmeg and 1/2 tsp of salt.
Whisk it together until it starts to bubble and thicken.
Once thickened, take it off the heat and add more salt and pepper to taste.
Layer the zucchini in a large casserole dish. Halfway through layering, sprinkle over 1/2 cup grated cheese, then top with the remaining zucchini.
Pour over the white sauce, then top with grated cheese and breadcrumbs.
Bake for 30-35 minutes until golden brown and bubbling.
Remove from the oven and let it stand for 10 minutes to cool before serving.