01 -
Combine ground beef, panko breadcrumbs, Italian seasoning, egg, ketchup, Dijon mustard, Worcestershire sauce, salt, black pepper, and minced garlic in a large mixing bowl. Mix gently until evenly incorporated.
02 -
Form the mixture into 4 oval patties, each approximately 2 cm thick.
03 -
Heat olive oil in a large deep skillet over medium-high heat. Add the patties and sear for 4 to 5 minutes per side, until each side is golden. Remove patties and set aside; interior may remain slightly undercooked.
04 -
Reduce heat to medium. Add diced onion to the skillet (add more olive oil if needed) and season with salt and black pepper. Cook, stirring, for 3 to 4 minutes or until onions begin to turn translucent.
05 -
Add sliced mushrooms, season lightly, and cook an additional 3 to 5 minutes, stirring occasionally, until golden and softened.
06 -
Add butter to the skillet and allow to melt. Sprinkle flour over the onions and mushrooms, then whisk to create a roux; cook for 1 minute to remove the raw flour taste.
07 -
Gradually pour in beef stock while whisking constantly to prevent lumps. Add ketchup and Worcestershire sauce, and season gravy with salt and black pepper to taste.
08 -
Return browned patties to the skillet, nestling into the gravy. Cover and simmer for 5 minutes or until patties are thoroughly cooked and gravy has thickened. Add extra broth or water if gravy becomes overly thick.
09 -
Plate patties and generous ladle of mushroom gravy over mashed potatoes or preferred accompaniment. Garnish with freshly cracked black pepper and chopped parsley if desired.