Slice the top and bottom from the eggplants. Cut into 1cm slices (circular or lengthways).
Put into a colander, sprinkle with salt and leave for 30 minutes. Wash and pat dry with kitchen towel.
Peel and thinly slice the turnips
Place the turnips in a medium saucepan with water. Bring to the boil, then cover and simmer for 10 minutes until the turnip slices are slightly soft.
Drain the turnips and set aside for assembly. Season the turnip slices with the garlic powder.
Slice the zucchini into 1cm slices (either circular or lengthways).
Heat the olive oil in a large frying pan or skillet and cook the eggplant and zucchini slices until golden. This will need to be done in batches. Set aside the slices.
Place a layer of the turnips on a bottom of a glass baking dish. Season with salt and pepper.
The next layer is the eggplant slices. Season with the herbs, salt and pepper.
Place half the zucchini slices on top and season well with the herbs, salt and pepper.
Spoon half the marinara sauce over the vegetable layers. Repeat the turnip, eggplant and zucchini layers and pour the remaining sauce on top.