Beaner, I made these over the week end along with grilled steak marinaded with Dancer's Cola Marinade #48292. It was a great combination. These potatoes were very good and another plus, NO CLEAN UP. It would also be a good camping recipe.
We make these, almost exacly, though for convenience squirt a line of squeezy cheese (don't what it is in the US - cheese whizz maybe) in the middle, ie layer half the potatoes and onions and we use garlic too, then a line of squeezy cheese, then the rest of the potatoes/onions/garlic, then a bit of olive oil and butter and wrap up and put on the barbie all at once. We usually do individual servings, ie each person gets a foil packet and we call them "Cheesy tatties".