1Preheat your oven to 375°F (190°C).
Peel and slice the potatoes into thin rounds.
Slice the tomatoes into thin rounds.
Grease a baking dish with the olive oil.
Arrange a layer of potato slices on the bottom of the dish.
Add a layer of tomato slices on top of the potatoes.
Sprinkle a pinch of salt, black pepper, and a bit of dried oregano over the tomatoes.
Repeat the layers until all the potatoes and tomatoes are used up, finishing with a layer of tomatoes.
Sprinkle the shredded mozzarella cheese evenly over the top layer.
Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and bake for an additional 15-20 minutes, or until the cheese is golden and bubbly.
Let the casserole cool for a few minutes before serving.