Whisk the flour, sugar, and salt together in a medium bowl. Using a pastry cutter or 2 forks, cut in the butter until the mixture resembles coarse pea-sized crumbs. Add the water and stir until the flour is moistened. Add 1–2 more Tablespoons of water if the dough seems dry. Turn the dough out onto a lightly floured work surface and, using your hands, work the dough into a ball. Flatten it into a thick disc. Wrap the dough disc in plastic wrap or parchment paper and refrigerate it for at least 1 hour, and up to 3 days.

Peel, halve lengthwise, and scoop out the seeded core of the pears. Remove the stem, including the bottom part of the stem. Place the pears in a medium bowl, and toss gently with lemon/orange juice, cinnamon, nutmeg, and ginger, until evenly coated. Place the bowl in the refrigerator until you’re ready to use the pears.

Melt the butter in a 10-inch oven-safe skillet over medium heat, or use a heavy-duty medium saucepan. Once the butter has melted, whisk in the brown sugar. Cook, whisking occasionally, for 3 minutes. Remove from heat and let cool for a few minutes while you roll out the crust.

Preheat oven to 400°F (204°C).

Roll out the chilled dough into a circle about 11–12 inches in diameter. Arrange the pears, cut-side up, in the skillet. Drape the pastry crust round over top of the pears. Gently tuck in the edges of the crust around the pears with a spoon. Dock (prick) the crust with a fork, to allow steam to escape.

Bake for 20 minutes, then reduce the temperature to 375°F (191°C) and bake for 25 more minutes, or until the crust is golden-brown.

Allow to cool for 10 minutes on a cooling rack, and then carefully invert the tart onto a large serving plate or platter. Slice and serve warm or at room temperature with vanilla ice cream, if desired.