In a medium-size bowl, combine crust mix, sugar, cinnamon, allspice and water. Toss with a fork until mixture can be gathered together. Roll out dough on lightly floured surface to an 11-inch circle. Slide onto waxed paper. Refrigerate.
Peel apples. Cut in half from stem to blossom end. Using a melon baller or measuring spoon, remove the core, and then cut out the stem and blossom.
Place apple halves, rounded side up, on a cutting board. Make thin cuts, slicing down to but not through the flat sides.
Heat oven to 375 degrees F. In a 10-inch ovenproof skillet, melt butter over medium-high heat. In bowl, stir together sugar, cornstarch and cinnamon. Sprinkle sugar mixture over butter in pan. Cook 2 minutes, stirring, until sugar is foamy. Carefully fit in apple halves, rounded side down. Cook 3 minutes. Reduce heat to medium. Cook another 7 minutes, until sugar has caramelized to a rich brown.
Remove skillet from heat. Drape crust over pan. Carefully tuck any overlapping edges between apples and skillet. Bake in 375 degree F oven for 30 to 35 minutes until crust is browned.
Cool tart in pan 15 minutes. Run a thin knife around edge between crust and pan. Place a large round or square platter on top of pan. Carefully invert tart onto platter, allowing caramel to drip onto apples and crust. Replace any apples that may stick to the pan. Serve slightly warm with whipped cream, if desired. Makes 12 servings.