In a large bowl, combine lean ground beef with an egg, breadcrumbs, salt, pepper, and grated shallot. Mix gently until just combined.

Divide the mixture into four equal portions and shape each into a patty about ¾ inch thick.

Heat a skillet over medium-high heat, add olive oil and butter. Sear the patties for about 5 minutes per side until browned.

Reduce heat to medium, add shallots and garlic to the skillet and cook for about 1 minute until fragrant.

Stir in mustard, salt, pepper, and flour. Cook for 1 minute, then add whiskey, scraping the pan for flavor.

Pour in beef broth and bring to a boil. Reduce heat and stir in cream until well blended.

Return the seared patties to the skillet, simmer for 5 minutes, garnish with chives, and serve.