Refigerate mixing bowl and beaters until well chilled; at least 30 minutes. Combine cream, vanilla, brandy and Grand Marnier in the chilled bowl and beat with electric mixer on medium speed for 1 minute. Add sugar and sour cream and beat on medium just until soft peaks form, about 3 minutes. Do not over-beat.
Nutritional info per tablespoon: 26cal; .1g pro, 2g carb, 2g fat (69%)
