1. Preheat the oven to 375°. 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.
2. 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.
3. Bake at 375° for 25 minutes. Sprinkle with powdered sugar, and cool in pan on a wire rack. Cut into squares.