Clip the leeks’ dark outer leaves with scissors. Remove root ends, quarter leeks lengthwise, then cut into medium dice. Soak leeks in 2 charges of water to remove grit; drain well.
Fry bacon in a large skillet over medium-high heat until crisp, about 7 minutes; drain, chop fine, and set aside. Pour off all but 2 tablespoons of the drippings; reserve 1 tablespoon of the remaining drippings. Add leek; sauté, seasoning with salt and pepper, until tender, 6 to 7 minutes. Add cream; continue to cook until thickened slightly, a few minutes.Stir in cheese.
When ready to serve, adjust oven rack to upper middle position and heat oven to 500 degrees. Arrange oysters on a rimmed baking sheet. Mix bacon with breadcrumbs, and remaining tablespoon of bacon drippings. Top each oysters 2 tablespoons of the leek mixture and 1 tablespoon of the breadcrumb mixture. Roast until leek mixture bubbles and crumbs are golden, about 8 to 10 minutes. Serve.
Recipe by Three Many Cooks at https://threemanycooks.com/recipes/salads-and-sides/roasted-oysters-with-leeks-and-bacon/