Slice the eggplant lengthwise.
Sprinkle with salt on both sides and leave for 30 minutes while preparing the filling.
Prepare the filling by heating a large pot and sautéing the onion and garlic in the oil until softened.
Add the tomato paste and cook for 2 minutes.
Add remaining ingredients and bring to a boil, reduce heat and simmer for 20-30 minutes.
Adjust seasoning to taste.
While the filling is cooking prepare the bechamel sauce by heating the oil in a pot and whisking through the flour. Cook for 2-3 minutes.
Slowly whisk the soy milk in stages, into the flour mixture until all incorporated and smooth.
Cook over medium heat while whisking until thickened.
Add the nutmeg, ½ cup parmesan cheese, salt and pepper, whisking until smooth.
Pat dry the aubergine slices with a paper towel.
Heat a skillet with oil and cook aubergine slices until golden on both sides.
Preheat the oven to 350 degrees F / 180 C.
To Assemble: Layer ½ of the aubergine slices over the base of a 15 inch x 10 inch baking dish.
Top with the filling and add another layer of eggplant.
Pour the bechamel sauce over top and sprinkle with the remaining cheese.
Bake in the oven for 40-50 minutes.
Once cooked remove from the oven and allow it to cool for 20-30 minutes before cutting into 10 pieces and serving.