Preheat oven to 350 degrees. Spray a 13 x 9 pan with non-stick spray.
Crust
Combine flour and powdered sugar in a food processor and pulse a few times until mixed.
Cut butter into cubes, then add to mixture in food processor and pulse until it is evenly distributed and looks like small beads.
Using the back of a large spoon, pat into the bottom of greased 13 x 9 in pan. Bake at 350 degrees for 15 minutes. When you remove it from the oven the crust will be moist, light in color and partially baked.
Filling
In a large bowl, beat the sweetened condensed milk, egg, and vanilla with an electric mixer until smooth.
Stir in chips and pecans until fully combined.
Spread evenly over crust and bake 20-25 minutes until golden brown.
Cool, then cut into bars. Store in sealed container.