Bilad al-Sham Kitchen - Potato casserole with spinach and mushrooms

Recipe ingredients:

6 mashed potatoes

1/4 cup of milk

A little oil or butter

Salt and Pepper

1 teaspoon of spices

Filling:

2 tablespoons of butter

2 tablespoons of oil

1 finely chopped red onion

2 minced garlic cloves

1 cup sliced mushrooms

4 cups of chopped spinach