Cook the rice according to package instructions and set aside.

In a pot, boil the diced potatoes until tender, then drain and set aside.

In a large skillet, melt the butter over medium heat. Add the chopped onion and sauté until translucent.

Add the grated carrot and sliced mushrooms to the skillet. Cook until the vegetables are tender.

Stir in the cooked potatoes and rice, mixing well.

In a small bowl, beat the egg with a pinch of salt and pepper, then pour it into the skillet, stirring constantly to combine.

Season the mixture with salt, black pepper, and oregano to taste.

In a separate saucepan, melt a tablespoon of butter over medium heat. Add the flour and stir to form a roux.

Gradually whisk in the cream, continuing to stir until the sauce thickens.

Pour the creamy sauce over the rice and potato mixture, stirring well to coat evenly.

Cook for a few more minutes until everything is heated through and well combined.

Serve warm and enjoy!