In a medium saucepan, add cranberries, ¼ cup sugar, and orange juice. Heat over medium-high heat and cook, stirring often, until cranberries begin to pop and thicken, 7 to 8 minutes. Remove from heat and stir in vanilla. Let cool for 30 minutes.

Preheat oven to 400°. Spray a 9-inch square tart pan with removable bottom with baking spray with flour.

On a lightly floured surface, unroll piecrusts and stack together. Roll into a 12-inch circle. Transfer to prepared pan, letting excess dough extend over sides of pan. Place cranberry mixture in prepared crust. Arrange pear slices on cranberries, fanning out decoratively.

In a small bowl, whisk together 3 tablespoons sugar, cornstarch, and pie spice. Sprinkle onto pears. Fold excess dough over pears.

In a small bowl, whisk together egg and 1 tablespoon water; brush onto dough. Sprinkle remaining 1 teaspoon sugar onto dough. Place tart pan on a rimmed baking sheet.

Bake for 30 minutes. Cover with foil and bake until crust is golden brown and pears are tender, 10 to 15 minutes more. Let cool completely in pan on a wire rack. Store in an airtight container for up to 2 days. Serve with sweetened whipped cream and garnish with fresh cranberries and rosemary.