Unroll 1 can of rolls; press into a lightly greased 9" x 13" pan. Beat egg yolk, cream cheese, and next 3 ingredients at medium speed of an electric beater until blended; spread mixture over dough in pan.
Unroll remaining can of crescent rolls on a sheet of wax paper; press into a 9" x 13" rectangle.
Place over cream cheese mixture.
Whisk egg white; brush over dough.
Sprinkle with pecans.
Bake at 375 for 25 minutes.
Sprinkle with powdered sugar, and cool in pan on a wire rack.