Place ground pork, rosemary, bread crumbs, parsley, and onion in a medium-size bowl; mix until well blended. Remove casings from sausage, and crumble into the mixture. Season with salt and pepper.
Sprinkle 1/4 cup grated Parmesan cheese into the bottom of pie shell. Spread pork mixture on top of cheese, and sprinkle with remaining Parmesan. Place top crust over filling, and crimp the edges together. Cut vents in top crust.
Bake in preheated oven for 15 minutes. Reduce heat to 350 degrees F (175 degrees C), and bake until crust is golden brown, about 35 to 40 minutes more. Cover edges of crust with foil if they begin to get too brown.