- Preheat oven to 350°F.
- Mix cream cheese, mayonnaise, Old Bay and ground mustard in medium bowl until well blended.
- Add crabmeat; toss gently.
- Spread in shallow 1 1/2-quart baking dish. Sprinkle with Cheddar cheese and additional Old Bay, if desired.
- Bake 30 minutes or until hot and bubbly. Serve with assorted crackers or sliced French bread.