I love scalloped potatoes and this is one of the better recipes I've tried.
Melt butter and blend in flour; add milk cooking until slightly thickened (can be done in Microwave).
Add shredded cheese and brie until melted.
Butter pan and layer 1/2 the potatoes, onions, bacon bits, and sauce then add the next layer. (You can do more layers if you want. End with sauce.).
Bake for 1 hour until tender.