Amidor says that pasta sauce should be stored upon opening in the refrigerator at 40°F or below. You can leave your store-bought sauce in the jar it came in, or transfer it to an airtight container.

Cook, stirring occasionally, until caramel is thick, syrupy, deep amber in color, and reduced to about 3/4 cup and apples are fork-tender, about 1 hour. Remove caramel from heat; turn off burner.