Line a rimmed baking sheet with parchment paper.

In a large saucepan, heat butter and granulated sugar over medium heat, whisking frequently until sugar dissolves. (Do not let sugar caramelize.) Whisk in ginger. Stir in pears; cook, stirring frequently, until pears begin to soften, 4 to 6 minutes.

Using a slotted spoon, transfer individual pear slices to prepared pan. Let cool completely before using, or cover and refrigerate for up to 24 hours.

Line a rimmed baking sheet with parchment paper.

On a lightly floured surface, roll Rough Puff Pastry Dough into a 14x12-inch rectangle, with one short side closest to you. Using a sharp knife, gently score the shape of a Christmas tree in dough. At center of short side closest to you, mark trunk of tree to 4 inches wide and 2 inches long. On opposite short side, mark center. Starting from center point at top, mark 4 (3-inch-tall) tree sections along one long side. Mirror marks on opposite long side. Once you’re happy with the shape, cut out tree, and remove excess dough. (See Note.) Transfer tree to prepared pan, and refrigerate for 30 minutes.

Preheat oven to 400°F (200°C).

Arrange pear slices on cold pastry, leaving a ½-inch border around edges.

In a small bowl, whisk together egg and 1 tablespoon (15 grams) water; brush onto edges of dough. Sprinkle with sparkling sugar.

Bake until pastry is golden brown, 25 to 30 minutes, rotating pan halfway through baking. Brush preserves onto hot tart. Let cool for 10 minutes. Serve warm or at room temperature.

Freeze cold butter until firm, 15 to 20 minutes.

In the bowl of a stand mixer fitted with the paddle attachment, beat cold butter, flour, and salt at low speed just until butter is coated with flour. With mixer on low speed, add ½ cup (120 grams) ice water in a slow, steady stream, beating just until dough comes together, about 1 minute, stopping to scrape sides of bowl and turn dough to help dough hydrate evenly. (There will still be large pieces of butter. It is OK if a few dry bits remain.)

Turn out dough onto a lightly floured surface, and roll into a 4-inch square. Wrap in plastic wrap, and refrigerate for 45 minutes to 1 hour.

On a lightly floured surface, roll dough into an 18x10-inch rectangle, lightly flouring surface and top of dough as needed. Fold dough in thirds like a letter. Rotate dough 90 degrees; roll into an 18x10-inch rectangle, and fold in thirds like a letter. Repeat procedure for a third and final turn. Wrap dough in plastic wrap, and refrigerate for at least 1 hour. (If at any point the butter is too soft after a fold, wrap in plastic wrap and freeze until butter is firm again, checking every 5 minutes.)