Zucchini, Tomato, and Onion Casserole


1 zucchini, thinly sliced
1 large tomato, thinly sliced
1 onion, thinly sliced
1/2 cup unsalted butter
1/4 cup red wine vinegar
1 teaspoon garlic salt
1 teaspoon dried basil
1/2 teaspoon dry mustard
2 cups grated Parmesan cheese


Preheat an oven to 350 degrees F (175 degrees C). Grease a 2-quart baking dish.

Arrange the zucchini slices, tomato slices, and onion slices in alternating layers in the prepared baking dish. Melt the butter in a saucepan over medium-low heat; stir the vinegar, garlic salt, basil, and mustard into the melted butter. Pour the butter mixture over the vegetables; sprinkle the Parmesan cheese over the dish.

Bake in the preheated oven until thoroughly heated, about 30 minutes.