1 cup pecan halves, divided
1-1/2 cups graham cracker crumbs
1/4 cup sugar
1/4 cup margarine or butter, melted
3 (8 oz) pkgs cream cheese, softened
1 (14 oz) can sweetened condensed milk (NOT evaporated milk)
4 eggs
1 (6 oz) pkg white chocolate baking squares, melted
2 tsp vanilla extract, divided
1 (21 oz) can cherry pie filling
Whipped cream or topping