Melt the 1 tablespoon of the duck fat in a large pan and fry the chicken livers until golden brown on each side and slightly pink in the middle.
Scrape into the bowl of a food processor.
Place the pan over high heat and fry the onions in the rest of the duck fat until soft and translucent.
Scrape into the food processor with the chicken livers.
Place the pan back onto the heat and deglaze with the brandy. Allow the brandy to reduce by half and scrape into the bowl with the chicken livers and onions.
Add the cream, nutmeg, salt and pepper and blend until smooth.
With the processor running, pour in the melted butter and blend until incorporated.
If you want the mousse to be smoother, pass through a sieve before placing into glass jars/small bowls.
To make the clarified butter, melt the butter over a gentle heat. When the butter is melted, allow it to sit for 5 minutes and allow all the milk solids to sink to the bottom of the pan.
Slowly pour the clear butter at the top through a muslin-lined sieve into a small measuring jug.
Pour the clarified butter over the surface of the chicken liver mousse.
Place the mousse in the fridge and allow to set for 2 hours before serving.
Serve with bread of your choice and caramelised onions.