Dice the unsalted butter and shortening and place it in the freezer while preparing the flour mixture. In a food processor fitted with a steel blade, pulse flour, salt, and sugar to combine; add the chilled butter and shortening pieces and pulse until the mixture resembles a coarse crumble with only a few larger pieces, about 8 to 12 pulses.

In a small bowl, combine 3 tablespoons of ice water, and 1 tablespoon of pure vanilla extract. With the machine running, pour the ice water mixture down the feed tube and pulse the machine until the mixture is evenly moistened and very crumbly; don't let the dough form into a ball in the machine.

How to Make the dough By Hand

Cut the butter and shortening into the flour in a large flat-bottomed mixing bowl using a pastry cutter or two forks; do not smash or smear. Instead, scrape butter off the pastry blender during the mixing process and continue mixing. If the fats are softening too fast, put the bowl in the refrigerator until it firms up, 2–5 minutes.

Sprinkling 3 tablespoons of liquid over the flour mixture; use a bench scraper or your hands to incorporate until the mixture begins to come together. Sprinkle in 1 more tablespoon of liquid and continue the mixing process. Squeeze a fistful of dough: if it holds, like wet sand, it’s ready.

If it falls apart, add 1 more tablespoon of ice water, squeezing the dough to check if it holds. Bring all the dough together, sprinkling dry bits with more small drops of ice water; the dough will look shaggy. Knead in the bowl just until incorporated).

Form and let it Rest: Turn the dough onto a work surface, and bring the dough together by hand. Shape into a flat disk and wrap in plastic wrap. Refrigerate for at least 30 minutes, preferably overnight. (Note: Dough can be refrigerated for up to 3 days and frozen for up to 1 month, tightly wrapped.)

Make the Apple filling: Peel the apples and cut them in half through the stem. Remove the stems and cores with a sharp knife and a melon baller. Slice the apples crosswise into ¼-inch thick slices. Place the apples in a large bowl and toss with the lemon juice, sugars, pure vanilla extract, cinnamon, and nutmeg. Set aside to let the flavors blend.

Roll the Dough: Lightly dust a work surface and a rolling pin with flour. Next, place the chilled pie disk on the work surface and let the dough sit on the countertop for 5 to 10 minutes so it's malleable enough to roll. Then, roll the dough into an 11-inch circle and gently transfer the dough to a parchment-lined baking sheet.

Sprinkle evenly 1 tablespoon of flour over the pastry, then working quickly, arrange the apple mixture in the center of the dough. Next, dot the apples with the 2 tablespoons of unsalted butter, then, using the parchment to guide you, fold the edges of the dough up and onto itself, one section at a time, patch up any tears by pinching a bit of dough from the edges.

Brush exposed dough with cream or egg wash and sprinkle with sugar. Chill the assembled apple galette in the fridge for 15 to 20 minutes. Meanwhile, preheat the oven to 350 °F and set an oven rack in the center position.

Bake: Bake galette for 55-65  minutes, until crust is golden brown and apples are soft; rotate the pan once during cooking. If bits of apple begin to burn before the crust is finished, simply tent a piece of foil over the fruit and continue baking. Note: It’s okay if some juices leak from the apple galette onto the pan. The juices will burn on the pan but the apple galette should be fine -- just scrape any burnt bits away from the galette once it’s baked.

While the apple galette cools, make the glaze; mix the apricot preserves with 1 tablespoon of water in a small microwave-safe bowl and heat in the microwave until bubbly. With a pastry brush, brush the glaze over the bottom and sides of the pastry shell. (This will help seal the crust and prevent it from getting soggy) Transfer the apple galette to a serving plate. Allow cooling and serve warm or at room temperature.