Peel and slice the potatoes into thin rounds.

Cut the broccoli into florets.

In a large pot, boil the sliced potatoes in salted water until they are just tender. Drain and set aside.

In a saucepan, melt the butter over medium heat.

Add the flour and stir continuously to form a roux. Cook for about 1-2 minutes.

Gradually add the milk while stirring constantly to avoid lumps. Continue to stir until the sauce thickens.

Add salt and rosemary to taste. Remove from heat.

Preheat your oven to 180°C (350°F).

Lightly grease a baking dish with vegetable oil.

Arrange a layer of potato slices at the bottom of the dish.

Spread a layer of broccoli florets over the potatoes.

Pour half of the Béchamel sauce over the vegetables.

Sprinkle half of the Parmesan cheese over the sauce.

Add another layer of potatoes and broccoli.

Pour the remaining Béchamel sauce over the top.

Sprinkle with the remaining Parmesan cheese and the mozzarella.

Bake in the preheated oven for about 25-30 minutes, or until the top is golden brown and the cheese is melted and bubbly.

Allow the dish to cool slightly before serving. Enjoy!