Peel and chop the celery bulb and steam on speed 8 in a little salted water until soft and the water has evaporated. Add the double cream, beef stock, reduced white wine and whipping cream, simmer briefly and blend very finely with a hand mixer. Stir in the brown butter, season to taste. Fold in the whipped cream. Peel the truffle and cut into thin slices. Pour the celery cream into soup cups and evenly distribute the truffle slices on top.
The truffle is only available in December and January. Of course, this soup is also delicious in spring and summer. Resort to the summer truffle during these months.