Preheat your oven to 400°F (200°C). Arrange the eggplant rounds and yellow bell pepper planks on a large baking sheet lined with parchment paper. Drizzle with olive oil and season evenly with salt, pepper, and dried oregano. Roast for 20 minutes until tender and slightly browned. Set the fresh, raw tomato slices aside on paper towels.

Heat a cast-iron grill pan or outdoor grill over medium-high heat. Brush your long zucchini planks lightly with olive oil and sear them for 2-3 minutes per side until prominent, dark char marks develop. Remove and set aside.

In a medium mixing bowl, combine 1 cup of ricotta cheese, half of the shredded mozzarella, and half of the grated Parmesan cheese. Stir in the minced garlic and fresh thyme leaves until smooth, thick, and fully combined.

Lower the oven temperature to 375°F (190°C). Lightly grease a small, deep baking dish with olive oil. Lay down the roasted yellow bell pepper planks across the bottom. Spread a spoonful of the cheese mixture evenly over the peppers. Add a layer of raw tomato slices, followed by another dollop of cheese. Layer the roasted eggplant rounds next, followed by the charred grilled zucchini planks. Smooth the remaining cheese mixture completely over the top zucchini layer.

Sprinkle the remaining half of the mozzarella and Parmesan cheese evenly over the top surface to build a dense cheese cap. Bake for 30 minutes until the center layers are bubbling hot. Turn the oven to broil for the final 2-3 minutes until the cheese crust turns a deep, bubbly, caramelized golden-brown.

Remove from the oven and let the dish rest undisturbed for 10-15 minutes. This allows the juices to settle and the cheese to firm up so it can be sliced into clean, pristine square stacks. Garnish with fresh thyme sprigs, slice, and enjoy.