Have three 8-oz. jars washed and hot. Prepare the lids according to the manufacturer’s directions. Combine the fruit, sugar and cardamom in a heavy non-reactive skillet. Use a potato masher to crush the fruit thoroughly. Let sit at room temperature for 1 to 2 hours, stirring occasionally to help the sugar dissolve. Add the butter and bring the mixture to a boil, stirring often to prevent burning. Reduce the heat to medium-low and simmer for 30 to 40 minutes, until the jam thickens. Ladle the jam through a wide-mouth funnel into jars. Attach the lids and process in a boiling water canner for 10 minutes.

Makes three 8-oz. jars or 48 servings.