Preheat your oven to 180°C (350°F).
In a large bowl, combine the softened Breadcrumbs with the Milk and let them sit for a few minutes until the crumbs absorb the liquid.
Heat a skillet over medium heat with a knob of Butter and a splash of Neutral Oil. Add a finely diced Onion and cook until softened and translucent; set aside to cool slightly.
To the bowl with the soaked crumbs add the Ground Beef, Ground Pork, the sautéed onion, beaten Eggs, a generous spoonful of German Mustard, chopped Parsley, Dried Marjoram, Sweet Paprika, and season with Salt and Black Pepper. Mix with your hands until everything is evenly combined but don’t overwork the meat.
On a sheet of parchment or a clean work surface, shape about half the meat mixture into a flattened log. Arrange the whole Hard-Boiled Eggs along the center, then fold and roll the remaining meat over them, sealing the seams to form a smooth loaf.
Heat a little more Neutral Oil in an ovenproof skillet over medium‑high heat. Brown the loaf on all sides to develop a crust, then transfer the skillet to the oven (or move the loaf to a baking dish) and bake for 40–60 minutes, until cooked through.
While the loaf bakes, make the sauce: in the same skillet (or a saucepan) melt another knob of Butter over medium heat and add one more finely chopped Onion, cooking until translucent. Sprinkle in the All-Purpose Flour and cook 1–2 minutes to remove the raw flour taste.
Stir in the Tomato Paste, then gradually whisk in the Beef Broth until smooth. Let the sauce simmer and thicken, then stir in the Heavy Cream to create a creamy, glossy gravy. Taste and adjust seasoning with additional Salt and Black Pepper as needed.
When the hackbraten is done, let it rest 10 minutes, slice to reveal the egg‑filled center, and spoon the warm tomato‑cream sauce over each slice. Garnish with extra chopped Parsley if you like and serve.
