Slice the clove of garlic very thinly. Put in a large skillet with the chopped onion and fry gently in butter until transparent. Cut the bacon in half and fry until nice and crispy. Peel and cook the potatoes until ready for mashing. Mash the potatoes and stir in some butter and cream to taste. Pile the mashed potatoes in a large serving bowl. With a pair of kitchen scissors, snip the scallions into the potato - half-inch lengths . Add the crispy bacon, onion and garlic. Mix lightly and season well with salt and black pepper. Serve hot.