Scalloped Potatoes and Onions

I recently found, what in my opinion, is a great scalloped potato recipe on AllRecipes.com. Some of you expressed interest in it, so I thought I would post it with my modifications. Thank you Peter for the awesome picture!

5 large potatoes sliced thin or however many potatoes it takes to fill my 2 1/2 qt circular casserole dish (precise I know)
3/4 c. chopped onion (if it is a small onion I use the whole thing, if it is large I will use half)
At least one clove of garlic (I tend to use more)
3 Tbs. margarine/butter (your choice)
1/4 c. all purpose flour
1 3/4 c. chicken broth
2 Tbs. mayonnaise/yogurt/sour cream (your choice)
3/4 tsp. salt and 1/8 tsp. pepper
Possible add-ins: parsley, chives, paprika, cheese (I use cheese and smoked paprika)

1) Saute onions & garlic in butter
2) Add flour, salt and pepper, stir until smooth
3) Add broth, mayonnaise, cook until bubbly and thick (about 2 minutes)
4) Grease casserole dish, layer potatoes and sauce, repeat until dish is full.
5) Sprinkle top with cheese, paprika, parsley, or whatever you desire.
6) Baked covered at 350 degrees for 1 hr or until potatoes are tender. I uncover for last 15 minutes or so to brown the cheese on top. Serves 6.