Peel the onions and cut into small pieces.

Peel the celery root and chop into small pieces.

Melt 1 tablespoon of butter in a large saucepan. Add the onions and cook, stirring frequently, until they become transparent.

Add the celery root pieces to the pan and stir to combine.

Add the broth to the pan and bring to a boil.

Turn the heat down to low and simmer for 20 minutes.

While the vegetables are cooking, fry the bacon. Drain on paper towels and chop into pieces.

Add the horseradish and cream to the vegetables. turn the heat up to medium and cook for another 5 minutes.

Puree using a stick blender. Alternatively,  transfer the mixture to a blender or food processor and puree, then return the mixture to the pot.

Add the bacon to the mixture, reserving some for garnish.

Add the sugar and cook for another 5 -8 minutes.

Season with salt and freshly ground pepper to taste.

Remove from heat, transfer to bowls, garnish with the remaining chopped bacon and chives and serve.