Place the drained cashews and vegetable broth in a food processor and blend until completely smooth, scraping the sides of the food processor with a spatula occasionally to make sure you get everything. This could take 5 minutes.
In the meantime, preheat a large pan over medium heat. Saute the onions and celery in the oil, along with a dash of salt. Cook until onions are nice and brown, about 10 minutes. Add the breadcrumbs and toss to coat onions and celery. Cook until the breadcrumbs turn a few shades darker, about 3 minutes.
Now is a good time to preheat your oven to 350 F.
Pour the cashew mixture into the pan and lower heat a bit. Mix well. Add lemon juice, several dashes black pepper and salt. Let cook for 2 minutes, it should begin to thicken. Taste for salt and adjust seasoning if needed.
Now we’ll put this baby together!
Lightly spray a 2 quart casserole rectangular with cooking spray (or lightly grease with olive oil). Pour half of the sauce into the casserole. Now arrange potatoes and eggplant into the casserole, dredging potatoes in sauce a bit as you layer. They should be in slightly overlapping layers, with a slice of bacon in between each potato.
Pour the remaining sauce over the potatoes. They should be mostly submerged. Use a rubber spatula to spread the sauce on if needed.
Seal tightly with tin foil and bake for about 45 minutes, or until potatoes are easily pierced with a fork. Remove foil and bake for an additional 15 to 20 minutes, until nice and brown.
Garnish with fresh chopped parsley and serve!