For the Dough, place flours, sugar and sea salt in food processor; cover. Pulse to mix. Add butter; pulse until resembles pea-size crumbs. With top part of food process cover removed, add 1 cup and 2 tablespoons ice-cold water while processing until a dough forms. Turn out dough onto lightly floured surface. Knead until dough is smooth. Shape into an 8-inch disk. Wrap in plastic wrap. Refrigerate 1 hour.
Preheat oven to 425°F. For the Filling, mix 2 ½ cups of the sugar, flour, apple pie spice and sea salt in large bowl. Add pears, barberries and almond extract; toss gently to coat. Set aside.
Roll dough between 2 pieces of parchment paper into a 6 x 12-inch circle. Place dough onto parchment paper-lined baking sheet. Spoon filling into center of dough, spreading to within 1 1/2 inches of edges. Fold edge of crust up over fruit, pleating or folding crust as needed. Brush crust with beaten egg and sprinkle with remaining ½ cup sugar and sliced almonds.
Bake the crostata on the middle rack of the oven 25 to 30 minutes or until pears are tender and crust is golden brown. Cool slightly on baking sheet. Cool completely on wire rack. Serve with ice cream or whipped cream, if desired.