Preheat oven to 425°. Crumble and cook sausage in medium skillet until browned; drain well on paper towels. Place pizza dough on lightly greased 12" pizza pan or baking sheet. Spread mustard over dough; top with Mozzarella cheese, sausage and onion. Place pickle slices evenly on top and sprinkle with cheddar cheese. Bake for 12 minutes or until crust is cooked through and cheese is bubbly. Cut into wedges or squares and serve hot. Refrigerate leftovers.