Combine cream cheese, sugar, egg yolk, and vanilla, stirring until well blended. Spread the crescent rolls on a greased cookie sheet; roll out with rolling pin until dough is flattened and seams are stuck together. Take the filling and spread it on the dough. Spoon pineapple over cheese mixture.

Fold one end toward the center; then fold the other end toward the center, overlapping 1 inch or more. Brush the slightly beaten egg white over edges to seal, then sprinkle nuts on the top. Bake at 350 degrees for 20 to 30 minutes. When cool, sprinkle with powdered sugar.