6 Tablespoons fresh lemon juice, divided
7 Pounds ripe pears
3 Cups (packed) golden brown sugar
1 Teaspoon freshly ground nutmeg
3/4 Teaspoon salt
Combine apple juice and 4 tablespoons lemon juice deep pot. Peel, core, and cut pears, 1 at a time, into 1/2- to 3/4-inch pieces; mix pears into juice mixture in pot as soon as pears are cut, to prevent browning. Cook over medium heat until pears release enough juice for mixture to boil, stirring frequently, about 15 minutes. Reduce heat to medium-low; cover and simmer until pears are very tender, stirring every 3 minutes or so, for about 20 minutes (mixture will splatter). Remove pot from heat. Press pear mixture through fine plate of food mill into large bowl (which I did, but regret... next time I will use my blender). Return pear puree to pot. Add 2 tablespoons lemon juice, brown sugar, nutmeg, and 3/4 teaspoon coarse salt. Bring to boil over medium heat, stirring until sugar dissolves. Reduce heat to medium and simmer uncovered until pear butter thickens and is reduced to 8 cups, stirring every 3 minutes to prevent scorching, for about 1 hour (yeah... I know... it's sort of insane).
Ladle pear butter into 8 hot clean 1/2-pint glass canning jars, leaving 1/4-inch space at top of jars. Remove air bubbles. Wipe jar threads and rims with clean damp cloth. Cover with hot lids; apply screw bands. Process jars in pot of boiling water 10 minutes.
Ever wonder why those jars of fruit butter -- in that speciality shop, where everything is overpriced, but you must walk out with something because the whole darn store is so inspiring -- are outrageously expensive? I'll tell you why. Labor.