Preheat oven to 426 degrees. Cook sausage, onion and bell pepper in large skillet over medium high heat for 6-8 minutes or until sausage is crumbled and no longer pink, stirring occasionally. Drain.
Spray a 15x10 inch baking sheet with cooking spray. Unroll pizza dough onto baking sheet and press into 14x10 inch rectangle. Spread 1/2 cup pizza sauce lengthwise down center of dough to within 1/2 inch of each short edge.
Spoon meat mixture evenly on top of sauce. Put a layer of pepperoni on top of that. Sprinkle cheese evenly over meat mixture. Pull up each long edge over filling and pinch edges together to seal. Pinch short ends together to seal.
In small bowl, combine the melted butter, mustard, Italian dressing and Italian seasoning. Whisk to combine. Use a pastry brush and brush the top and sides of the calzone with the mixture.
Bake 15-18 minutes or until deep golden brown. Heat remaining 1 cup of pizza sauce in covered container in microwave on HIGH for 1 1/2 minutes or until hot. Cut pizza bake into 8 slices. Serve sauce over slides.