01 -
Preheat the oven to 350°F. Gently mix beef, breadcrumbs, beaten egg, finely diced onion, salt and pepper; stop when distributed rather than kneading densely.
02 -
Shape six to eight evenly thick oval patties. Keep raw portions chilled until the skillet and remaining ingredients are ready.
03 -
Brown patties in batches in an oven-safe skillet, turning carefully. Transfer to a plate briefly while making the gravy; proceed directly with cooking. Drain excess rendered fat.
04 -
Melt the measured butter in the skillet, soften the sliced onion, then stir in flour and garlic powder. Cook while stirring for about two minutes. Gradually whisk in broth, then cream, smoothing each addition.
05 -
Return patties to the gravy in one layer. Cover and bake, beginning temperature checks around 30 minutes; larger patties may need longer. Every center must reach 160°F. Uncover briefly if the sauce needs reducing, and do not continue to a fixed hour if the patties are already done.