I forgot to take a picture (I was rushing out the door with these little gems hot from the oven).
Here is what I did:
I sliced potatoes and purple onions (as many or as little as you like... I know, I know it's very irritating for the exact measuring people out there), about enough to do 2 thin layers of each in a 9"X13" Pyrex baking dish.
Then in a big pot I made a roux with butter (melted and almost about to turn brown), garlic (powdered or real), flour and milk. I melted the butter and sautéed the garlic first. Then I added the flour until I had a thick paste. Then I added the milk slowly until I had a smooth and slightly thick sauce. Do not let it boil. I then added smoked guyere cheese and some regular white cheddar cheese. I continued to cook and stir until the cheese was all melted. I put this on top of my potatoes and then sprinkled more cheese and some chopped up bacon on top. Cover with foil and toss in the oven at 350* F or 175/200*C for about an hour. Take the foil off the top for an additional 10 minutes at the end and serve... it was rich, cheesy, buttery, smoky goodness!!!