Preheat oven to 400ºF and lightly grease a cast iron pan; sprinkle 1 cup breadcrumbs, cover the bottom evenly and set aside.
In a skillet over medium heat, add oil and when hot, add onion; sauté for 5 minutes. Add garlic and red pepper flakes; sauté for 1 minute. Pour in red wine and cook for 1 ½ to 2 minutes or until absorbed. Spread onion mixture on the bottom of the prepared cast iron pan; set aside.
Using a mandolin, slice each vegetable with the same thickness of 1/4–inch. Precook squash and russet potato slices in the microwave for 5 minutes on “High”; let them cool off.
Stack vegetables starting with russet potato slice then a tomato slice followed by squash and zucchini; repeat the same order so the tian looks well balanced in color. Arrange stacks evenly around the outside edge working towards the middle. Pour lemon juice over the veggies and sprinkle with Herbes de Provence, sea salt and black pepper. Cover tightly with foil and transfer to the preheated oven; bake for 60 minutes or until tender.
Meanwhile, make the topping by stirring gruyere cheese, breadcrumbs and clarified butter together; set aside.
After an hour, remove tian from the oven as well as foil. Sprinkle topping mixture evenly and return tian to the oven, uncovered; bake for 15 minutes or until cheese is melted. Remove from the oven and let sit for 10 minutes before serving. Makes 8 servings.