I cannot get enough recipes with apples this time of year. This one is best served with a little pareve ice cream or pareve whipped cream. This is a modified recipe from a restaurant called Sea Glass on Cape Cod.
2-1/2 cups all-purpose flour
1 teaspoon fine sea salt
1 teaspoon sugar
1 cup (2 sticks) chilled margarine butter, cut into 1/2" cubes
¼ teaspoon butter extract (optional, this is pareve and made by McCormick)
1/2 cup sugar
2 tablespoons cornstarch
1/2 teaspoon ground cinnamon
1/2 teaspoon ground nutmeg
Pinch of fine sea salt
2-1/2 pounds Golden Delicious apples (about 5 large), peeled, halved, cored, cut into 1/4"-thick slices (about 7 cups) or use another firm, fresh local apple
2 tablespoons fresh lemon juice
1 large egg
2 tablespoons raw sugar
2 tablespoons pure maple syrup
Pareve vanilla ice cream or pareve whipped cream
Place flour, salt, and sugar in a food processor; pulse to blend. Add margarine and butter extract; pulse just until coarse meal forms. Add 1/4 cup ice water; pulse until dough forms clumps, adding more ice water by teaspoonfuls if dough is dry. Gather dough into a ball; flatten into a disk. Wrap dough in plastic and chill 1 hour.
DO AHEAD: Crust can be made 1 day ahead. Keep chilled. Allow to stand at room temperature for 15 minutes to soften slightly before rolling out.
Preheat oven to 400°. Place a large sheet of parchment paper on a work surface. Roll out dough disk on parchment paper to 15" round (some of dough will extend over edges of paper).
Whisk sugar, cornstarch, cinnamon, nutmeg, and salt in a large bowl. Add apples and lemon juice to bowl with sugar mixture; toss to coat apples evenly.
Transfer apples to crust, mounding in center and leaving a 3" plain border. (Scrape out any juices from bowl and drizzle over apples. Fold crust edges up over outer edges of filling, crimping dough and folding and pleating as needed to fit. Slide crostata and parchment onto a large rimless baking sheet. Crack egg into a small bowl. Using a fork, beat egg just to blend. Brush crust edges with beaten egg, then sprinkle crust with raw sugar.
Place crostata in oven and bake until juices in center are thick and bubbling, about 1 hour. Let cool for 5 minutes. Run a long, thin knife or offset spatula around edges of crostata to loosen from paper and to prevent it from sticking to the paper. Transfer baking sheet with crostata to a wire rack. Brush apples generously with maple syrup. Let crostata cool.
Cut crostata into wedges. Place wedges on plates and serve with pareve ice cream or pareve whipped cream.