Preheat oven to 400 degrees. Melt the butter and olive oil in a large cast iron or other oven safe skillet over medium-high heat. Add sliced onions and sure 3-5 minutes until soft. Add 4 TBSP beef stock and continue to cook, stirring occasionally for about 15 minutes.
Reduce heat to medium and add a drizzle of olive oil to the skillet and cook pork chops, about 3-4 minutes per side until golden brown. Transfer them to a plate
Return cooked onions to pan and sprinkle with flour. Stir to coat onions with flower and cook about 1 minute. Add remaining beef stock and stir often until boiling. Season with a pinch of salt and pepper
Transfer pork chops back into the pan, spooning some of the beef stock/onions over the tops of the pork chops. Bake 8-10 minutes.