Cut the onions and scatter on the bottom of a pan. Lay the potatoes on top (slice thinly as possible).
Sprinkle flour evenly on top of Step 1, then add the uncooked macaroni. Sprinkle in the other ingredients (chicken, mushrooms, anything works )
Add the milk and water, and flavor with salt and pepper. Add the butter last and simmer on medium heat. Mix the top layer to make sure that everything is well-incorporated, then cover with a lid. Once it comes to a boil, reduce to low heat.
Mix occasionally, and once the macaroni has softened and the sauce is creamy, it's complete (I used thin macaroni, which took 20 minutes to cook). Taste, and if you find the flavor to be lacking add consomme.
I garnished the dish with microwaved broccoli. I eat it like this, but you can add cheese and then bake in a oven until golden brown.
Story Behind this Recipe
This is the gratin recipe my mother makes often. It seems she learned this long ago from a friend. When I learned how simple it was, I think I may have become a little ungrateful . Note: It's a bit more effort, but if you sift in the flour, it'll mix easily. But you don't have to.
If you'd like an even richer flavor, use 200 ml each of milk and heavy cream (in this case, omit the butter). Even with just milk, the dish will be creamy enough. This is seasoned very lightly . Since you can add whatever ingredients you like, you may need to adjust the taste with consomme, which I didn't list.