Preheat oven to 425 degrees F. Line a 15x10x1-inch baking pan with parchment paper; set aside. Unfold puff pastry on a lightly floured surface. Roll pastry into a 14x10-inch rectangle; transfer to the prepared baking pan. Prick pastry all over with a fork. Bake about 10 minutes or until center is set. Remove from oven; lightly press center with a spatula.
Meanwhile, in a small saucepan cook potatoes, carrot, broccoli, and onion in boiling salted water for 3 minutes; drain.
Spread cream cheese over partially baked pastry. Top with vegetables and shredded cheese. Bake for 8 to 10 minutes more or until pastry is golden and shredded cheese is melted. Sprinkle with fresh herbs. Cut into rectangles.