Preheat the oven to 350°.
Cut the butter into the flour, using a pastry blender or fork. (This will make soft crumbs.)
Stir in the pecans.
Press this mixture into the bottom of a 9x13 pan.
Bake for 18- 20 minutes, until it is lightly browned.
Let it cool completely before filling.
When the crust is cool, prepare the filling.
Mix the cream cheese and powdered sugar with an electric mixer.
Fold in the whipped topping with a rubber spatula, stirring to combine.
Spread this over the cooled crust.
Spread the sliced peaches over the cream cheese mixture.
Cover and refrigerate until ready to serve.