In a medium saucepan, combine unsalted butter and sunflower oil over medium heat. Once the butter has melted and begins to bubble, add finely chopped shallots, sautéing for about 3-4 minutes until they turn soft and translucent.

With the shallots softened, sprinkle in freshly crushed black peppercorns and a pinch of salt, stirring for an additional minute.

Pour in brandy or cognac, scraping the bottom of the pan. Allow the alcohol to cook off for about 2 minutes.

Add beef stock and Worcestershire sauce to the pan, increasing heat to bring to a gentle simmer. Let it cook for about 5 minutes.

Lower heat and stir in double cream or half-and-half. Simmer for an additional 2-3 minutes.

Taste and adjust seasoning if necessary before serving.