Preheat oven to 350 degrees 1. Place dough on lightly floured surface. Roll into 12 x 8 inch rectangle with rolling pin. 2. Top dough evenly with ham, overlapping slices slightly and leaving a ½ inch border around all sides. 3. Mix cheese, onion, dressing; spread over ham. 4. Moisten edges of dough with water. Starting at one of the long sides of dough, fold 1/3 of the dough over filling. Then repeat with other long side of dough. Firmly pinch ends of dough together to seal. Place, seam-side down, on lightly greased baking sheet. 5. Cut 3 diagonal slits in top of dough. Brush with egg; sprinkle with parmesan cheese. Bake 35 to 40 min. or until golden brown. Cool 10 min. before cutting.