In a large bowl, combine grated onion, ground beef, breadcrumbs, salt, pepper, heavy cream, and egg. Mix gently until just combined.

Shape the mixture into 4 patties, each about ¾ inch thick, and make a small indentation in the center.

Heat olive oil and butter in a skillet over medium heat. Sear the patties for 4-5 minutes on each side until golden brown.

In the same skillet, reduce heat and sauté minced garlic and diced onion for about 2 minutes until translucent.

Sprinkle in salt, pepper, and flour; stir for a minute. Gradually add chicken broth and simmer until thickened.

Lower heat and stir in heavy cream and dill. Bring to a boil, then let simmer to thicken.

Return patties to skillet and simmer in sauce for 5-6 minutes until heated through.

Serve the Hamburger Steaks on plates, drizzling with sauce and garnishing with additional dill and pepper.