manteiga sem sal

* 4 slices bacon, diced * 2 tablespoons unsalted butter * 1 small onion, finely chopped * 2 celery stalks, finely chopped * 2 tablespoons all-purpose flour * 4 cups chicken stock * 1 cup whole milk * 1 cup heavy cream * 4 russet potatoes, peeled and diced into 1/2-inch cubes * 1 teaspoon …