To make the white sauce:
Heat a saucepan, melt butter, add chopped garlic and stir for a minute.
Add flour and whisk continuously. Cook for 1 minute and add salt.
Add milk; cook for 5 minutes or until thickened. Stir constantly. Add 2 tbsp. grated cheese, a pinch of pepper powder. Cook and stir for 1 minute or until the cheese melts. Keep aside.
For Baking:
In the deep baking dish, put the corn-spinach mixture. Pour half of the white sauce and layer the sliced potatoes.
Then pour the remaining sauce. Sprinkle the remaining regular cheese and mozzarella or pizza cheese on top.
Cover the baking dish with a silver foil and bake at 180-degree Celsius for 20 minutes.
Remove the foil and bake it again for 20 minutes or until its golden brown on top. Serve hot with rice or bread.