Combine the flour, cold butter, shortening, and salt in a food processor.

With the food processor running, slowly drizzle in the ice water.

Pulse the food processor 8 to 10 times, or until the dough comes together and forms a ball.

Remove the dough from the food processor, divide it into two equal parts, and wrap each half tightly in plastic wrap.

Refrigerate the dough for at least 30 minutes.

Combine the apples, brown sugar, flour, cinnamon, nutmeg, and salt in a large mixing bowl and stir until evenly coated.

On a lightly floured surface, use a rolling pin to roll out one disc of the refrigerated dough into a circle about 10 inches in diameter; the edges do not need to be perfectly even.

Transfer the rolled dough to a parchment-lined baking sheet.

Pour the apple filling into the center of the dough, leaving a 1-inch border of dough uncovered around the edge.

Fold the edges of the dough up and over the outer edge of the filling, pleating as needed.

Bake in the preheated oven for 25 to 30 minutes, until the crust is golden brown and the apples are tender when pierced with a fork.

Remove the baking sheet from the oven and let the tart cool on the baking sheet for at least 10 minutes before transferring it to a serving plate.