In a large saucepan over medium-low heat, melt the butter. Add onions, salt and pepper.

Cook until the onions are caramelized and golden brown. This will likely take 45-60 minutes. Make sure to stir from time to time to be sure the onions don’t stick to the bottom or burn. This is time consuming, but is essential to get the wonderful flavor of this gravy.

While the onions are cooking, in a small bowl, combine the cornstarch and ½ cup of the chicken broth. Set aside.

Once the onions are golden brown, add the cognac and wine. Let it boil for a minute or two, then add the chicken stock and cornstarch mixture. Stirring constantly as you add these, you will notice that it thickens quickly.

Add the cream, fish sauce and worcestershire and stir to combine.

Once it has thickened to your liking, it is ready to serve! Just before serving you can add the fresh herbs if you like.