Steps
1. Preheat your oven to 180°C (350°F).
2. In a skillet, heat olive oil over medium heat and cook the diced chicken until browned and cooked through. Season with salt and pepper.
3. Add fresh spinach to the skillet and cook until wilted. Remove from heat.
4. In a saucepan, melt butter over medium heat. Stir in flour and cook for 1 minute.
5. Gradually whisk in milk, cooking until the sauce thickens. Season with salt, pepper, and nutmeg.
6. Combine the chicken and spinach with the béchamel sauce, stirring well.
7. Pour the mixture into a baking dish and sprinkle grated cheese on top.
8. Bake in the preheated oven for 20-25 minutes or until the cheese is golden and bubbly.