Preheat oven to 375F. Scrub pumpkins and cut them into 5-inch square pieces. Discard stems and any seeds. Place pumpkin in a single layer, skin side up on a foil-lined baking sheet. (Use to if necessary to maintain a single layer of pumpkin.) Cover with foil and roast for 1 to 1 1/2 hours or until tender. Allow to cool. Scoop pulp from the rind and puree in batches with a blender or food processor. Place puree in a colander lined with cheesecloth. Allow to stand 1 hour to drain excess liquid.
In a heavy 5-quart pot, combine pumpkin puree, maple syrups, apple juice, lemon juice, ginger, cinnamon, nutmeg, and salt. To to a boil. Reduce heat and simmer, uncover, for about 25 minutes, or until thickened. Stir often.
Ladle pumpkin into hot half-pint glass canning jars, leaving 1/2 inch headspace. Wipe the rims, place lids, and screw lids on to just fingertight.
Can using a water bath canner. Make sure that the water is at least 2 inches above jar lids. Process 30 minutes. Remove jars to a flat, heat-proof surface. Allow to cool for 24 hours. Check seals. Label and store.
