Combine the pastry ingredients in a mixing bowl, stirring and mashing with a fork until fairly consistent, then work with fingertips until everything is absorbed in a coherent mass. Transfer to a floured pastry marble or board and knead for a couple of minutes, pushing small sections of the mass against the floured surface and away from yourself with the heel of your hand; gather it together in a ball and begin again—it will, at this point, be soft and sticky; wrap it in plastic or waxed paper and refrigerate for at least a couple of hours.
If using a cookie sheet, butter it lightly. If your oven is fitted with a solid metal plaque, use it, removing it from the oven before heating and lining it with parchment paper or aluminum foil, the surface lightly buttered.
Roll out the dough as rapidly as possible, being certain that it is always lightly coated with flour—it sticks easily. Turn it over two or three times while rolling—the given proportions should form a circular sheet approximately 14 inches in diameter. Fold it and transfer it to the buttered plaque; then spread it out. It is extremely fragile; if it should tear, don’t worry—patch it up. Roll the edges up to form a border, pressing all around with the tines of a fork.
Halve the apples, core them and peel them (don’t do it ahead of time—they will turn brown). Slice each half crosswise into ⅛- to ¼-inch thicknesses and arrange the slices, starting just inside the border of the pastry, in concentric circles, slices overlapping and circles overlapping. Sprinkle the surface with sugar and bake in a 350° oven for about 1 hour, checking progress regularly after 45 minutes. Paint the surface of the apple slices with the pureed jam, using a pastry brush—or simply dribble it around with a teaspoon, smearing it regularly over the surface of each apple slice with the back of the spoon. Slip the tart onto a large flat, round platter; serve hot, tepid, or cold.