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