1Juice pears through the low pulp screen. Strain through a fine mesh sieve to remove any large chunks or skins. You should have about 1 cup of juice.
2In a small saucepan, cook juice, stirring occasionally, over medium-high heat until thick and butterscotch in color and reduced to 1/4 cup, about 10 minutes. Set aside.
3In a small, high-sided saucepan, combine sugar, 2 tablespoons water, and cream of tartar, stirring until sugar has dissolved. When the mixture starts to boil, stop stirring and cover the pan for 2 minutes (the steam buildup will dissolve any stray sugar crystals on the side of the pan). Remove cover and cook, without stirring, for about 8 to 10 minutes or until sugar caramelizes to the color of light beer, swirling the pan as needed to ensure an even color throughout.
4Remove from heat and whisk in reduced pear juice, cream, butter, and salt until smooth (mixture will bubble vigorously, so pour carefully to prevent spattering). Stir in pear liqueur and let cool. Caramel sauce will keep, refrigerated in a glass jar or airtight container, for up to 2 weeks. Re-warm prior to serving.