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

Divide the beef mixture into four portions and shape each into patties about ¾ inch thick.

Heat a skillet over medium heat with olive oil and butter. Sear patties for about 4-5 minutes per side until cooked through.

Remove patties and in the same skillet, sauté diced onion and minced garlic for about 2 minutes until fragrant.

Stir in salt, black pepper, and flour, cooking while stirring for 1 minute to avoid lumps.

Gradually add chicken broth, stirring to deglaze the skillet. Simmer for 2-3 minutes until thickened.

Reduce heat, stir in heavy cream and chopped dill, cooking for another 3-4 minutes until sauce thickens.

Return hamburger steaks to the skillet, simmer for 5-6 minutes in the sauce. Serve hot with mashed potatoes or crusty bread.