Heat oven to 375°F. Spray cookie sheet with butter-flavored nonstick cooking spray. Unroll dough onto sprayed cookie sheet. Press to form 14x12-inch rectangle.
Reserve 2 tablespoons of the Parmesan cheese. Sprinkle remaining Parmesan cheese lengthwise in 4-inch-wide strip down center of dough to within 1/4 inch of each end. Top with ham, chicken, mushrooms, bell pepper, cheeses and salad dressing.
Bring one long side of dough up and over filling, completely covering filling. Repeat with remaining long side, overlapping dough. Press edge to seal. Fold ends under. With sharp knife, cut 5 slits in top of dough to allow steam to escape. Sprinkle with reserved 2 tablespoons Parmesan cheese.
Bake at 375°F. for 18 to 24 minutes or until golden brown. Cool 5 minutes. Cut into slices.