Preheat smoker to 425F and generously coat the tops and bottoms of the eggplant slices with olive oil, salt & pepper in a rimmed baking sheet.
Arrange the slices directly on the smoker and smoke until cooked through and tender then flip to the other side and cook until the same (~15 min total).
Rearrange the slices back onto the baking sheet and stack a spoonful of marinara sauce, a mozzarella slice and a basil leaf on half the slices. Then stack another eggplant slice on top of each before adding an additional spoonful of marinara topped with grated parmesan cheese.
Smoke at 425F for 10 min, or until cheese is melted.
Remove from smoker and optionally top with any remaining basil, sauce, salt, pepper, etc. Serve immediately.
Notes
While Cam and I like to use a pellet smoker, any indirect heat source will work just as well - charcoal, gas grill, or even the oven. Smoking adds an extra layer of flavor to the cheese, though a charcoal grill can deliver the same results with a bit more effort by shifting the coals for indirect heat.