- cooking spray
- 2 baking potatoes, cut into1/2-inch slices
- salt and ground black pepper to taste
- 3 large yellow summer squash, cut into 1/2-inch slices
- 4 large tomatoes, cut into 1/2-inch slices
- 1 sweet onion, cut into 1/4-inch slices
- 2 Tbs butter
- Preheat oven to 375 degrees. Spray a 9×13-inch baking pan with cooking spray.
- Cover the bottom of the baking pan with a layer of potato slices; season with salt and pepper. Place squash slices on top of the potatoes; repeat seasoning. Lay tomato slices on top of the squash; repeat seasoning. Continue layering the vegetables in this pattern, seasoning each casserole layer. Scatter onion over the casserole; dot with butter.
- Bake in the preheated oven until the top is golden brown and the potatoes are soft, about 1 hour.