12 oz. Granny Smith apples (about 2 large)
4 pounds peaches, peeled, pitted and diced (about 6 C.)
2 C. granulated sugar
3 T. strained fresh lemon juice

Sterilize jars by boiling for 10 minutes in a large canning pot; leave them in the pot to stay hot. Put a small plate in the freezer. Put the flat lids in a heat-proof bowl. Quarter and core the apples, reserving the cores and seeds. Tie cores and seeds in a cheesecloth bag and set aside. Put the peaches and sugar in a wide, 6- to 8-quart preserving pan or other wide shallow pan. Bring to a simmer over medium-high heat, stirring frequently, and continue to cook until the juices just cover the peaches, about five minutes. Pour into a colander set over a large bowl. Stir peaches gently to drain off juice. Return juice to pan, along with the apples and the cheesecloth bag. Bring to a boil over high heat and cook, stirring occasionally, until syrup is thick and reduced, about 15 minutes.

Return peaches and any accumulated juices to pan, along with the lemon juice. Bring back to a simmer and cook, stirring frequently, about 15 minutes, until peaches are very tender and a small dab of jam spooned onto the chilled plate and returned to the freezer for a minute becomes somewhat firm. (It will not gel.) Remove from heat. Remove apples and trimmings, and stir gently to distribute fruit in the liquid. Ladle hot water from the canning pot into the bowl with lids, and remove jars from hot water bath.

Ladle hot jam into the jars, leaving 1/4 inch head space at the top. Wipe jar rims with wet paper towel, if necessary. Put a flat lid and ring on each jar, and tighten until snug. Return the jars to the canning pot, making sure water covers jars by at least 1 inch. Bring to a rolling boil and boil for five minutes. Remove jars from the pot and let sit untouched for 12 hours. (After one hour, check to see if the jars have sealed. If the center of the lid can be pushed down, it hasn’t sealed. Immediately move any unsealed jars to the refrigerator. They should keep for a couple of weeks.) When you’re all done, label your pretty little jars and store them in a cool, dark place.