In a nine-by-13-inch baking pan, toss together the pears, ginger, granulated sugar, and butter. Roast, stirring occasionally, for one to one and a half hours, or until the pears are soft when pierced with a knife tip and golden. Let cool completely. (The pears can be roasted up to five days in advance and stored in an airtight container in the refrigerator.)
Remove the dough from the refrigerator. On a well-floured work surface, roll out the dough into a circle about 12 to 14 inches in diameter and a quarter inch thick. Place the dough circle on the prepared baking sheet.
Using the back of a spoon or a small rubber spatula, spread the frangipane in the middle of the dough round in a circle about eight to nine inches in diameter, leaving a three-inch border uncovered.
Place about eight pear halves, cut side down, in a circle in a single layer on top of the frangipane, lining them up with the edge of the frangipane and with the stem ends pointing toward the middle. Place one or two pear halves in the center to cover the frangipane circle completely. Sprinkle three quarters of a cup (75 grams) of the cranberries evenly on top of the pears. Top the first layer of pears with a second layer of pears, using about seven halves and reserving one pear half, arranging them in a smaller concentric circle. Sprinkle the remaining quarter cup (25 grams) cranberries evenly on top of the second layer of pears.
Place the reserved pear half on a cutting board. Using a paring knife, and starting at the squat bottom end, cut four or five lengthwise slices, stopping just short of the stem end. Fan the slices, and place the pear half in the center of the second layer of pear halves. Starting at one side of the crostata, fold the three-inch border of dough up and over the fruit, forming six to eight loose pleats around the perimeter and pressing the pleats firmly together onto the fruit. The center of the crostata will remained exposed in a three- to four-inch circle, showing off the fanned pear. Refrigerate the assembled crostata for at least one hour before baking. (At this point, the crostata can be covered with plastic wrap and stored in the refrigerator for up to one day before baking.)
Position a rack in the center of the oven, and heat the oven to 350 F.
Brush the pleated pastry with the beaten egg, then sprinkle evenly with the sanding sugar. Bake for about one hour and 20 minutes, or until the pleats are golden brown. Make sure all of the folds are evenly browned, so there are no chewy underbaked bits of dough in the finished crostata. Let cool on the pan on a wire rack for at least two hours. Serve warm or at room temperature.
The crostata can be stored in an airtight container at room temperature for up to two days.
Makes about 1 cup
• 1/3 cup (50 grams) blanched whole almonds or 1/2 cup (50 grams) almond flour
• 1/4 cup (1/2 stick/56 grams) unsalted butter, at room temperature
• 1/4 cup (50 grams) sugar
• 1 egg
• 2 teaspoons unbleached all-purpose flour
• 1/8 teaspoon vanilla extract
• pinch of kosher salt