In food processor, blend together Cheddar cheese, cream cheese and butter until combined.
Add orange rind and juice, mustard and nutmeg; blend just until thick and creamy.
Spoon into 8-inch (2 L) plastic wrap-lined springform pan, smoothing top.
Cover and refrigerate for at least 8 hours or until chilled and firm.
(Cheesecake can be refrigerated for up to 3 days.)