Bring the cream and garlic to a boil, then simmer vigorously, reducing the cream to 3/4 cup. Remove from heat and remove the garlic. Let the cream cool slightly, season taste.
Transfer the chard to a buttered gratin dish, sprinkle with the crumbled bacon and cheese, then top with the cream and breadcrumbs. Bake at 400 until bubbly, remove, then let rest 10 to 15 minutes.