Ingredients
6 tablespoons extra-virgin olive oil, plus more for baking dish
2 cups whole milk
1 1/2 cups quick-cooking polenta
Coarse salt and freshly ground pepper
1 large leek, white and pale-green parts only, thinly sliced into half-moons and washed well (2 cups)
1/2 small eggplant (6 ounces), cut into 1/8-inch rounds
1 large zucchini (10 ounces), cut into 1/8-inch rounds
2 medium tomatoes (10 ounces), cut into 1/8-inch rounds
1 cup coarsely grated (on the large holes of a box grater) Gruyere
Preparation
Preheat oven to 425 degrees. Brush a shallow 2-quart baking dish with oil. Bring milk and 2 1/2 cups water to a simmer in a medium pot. Whisk in polenta; cook, whisking, 1 minute. Season with salt and pepper. Transfer to prepared dish, spreading in an even layer.
Layer half of leek, eggplant, zucchini, and tomatoes over polenta. Drizzle with 3 tablespoons oil; season with salt and pepper. Scatter with half of cheese. Repeat layering with remaining ingredients, omitting cheese.
Bake 30 minutes. Press vegetables down with a spatula; sprinkle with remaining cheese. Bake until vegetables are knife-tender and edges are caramelized, about 35 minutes more. (If cheese is darkening too quickly, tent with foil.) Let cool slightly before serving.
