Making the topping:
In a bowl, mix flour, sugar, brown sugar, gingersnaps, ginger, and salt. Stir in melted butter until large crumbs form.
Making the filling:
Preheat oven to 350 degrees. In a large bowl toss pears, apples, cranberries, lemon juice, lemon zest, and vanilla. In a small bowl toss sugar with cornstarch and then stir this mixture into the fruit.
Pour filling into pie crust, cover with topping. Set pie on foil lined baking sheet. Bake for 1 ½ hours or until golden brown and filling is bubbling over.
Excellent served hot with a scoop of vanilla ice cream!