Preheat oven to 350°F. In a food processor, blend the graham crackers and pecans until finely chopped. Stir in butter and sugar until well combined and press into the bottom of a 13x9 pan. Bake for 8 minutes and let cool completely.
In a large bowl, beat cream cheese and powdered sugar until smooth. Using 1 container of whipped topping, beat in about 1 cup so there are no lumps. Fold in the remaining whipped topping from the container and spread the cream cheese mixture over crust.
Add the blueberry pie filling in an even layer. Top with remaining container of whipped topping. Garnish with chopped pecans if desired. Cover and chill for at least 2 hours or overnight.