Using the same skillet (preferable a deep sided skillet) add 1 Tbsp butter to the existing oil from the searing of the meat patties, stirring til melted
Over medium heat, Add the onion half slices and saute (stirring carefully) til translucent and caramelized which will take about 10-15 minutes
About 5 minutes before onions are done, add the mushrooms and watch carefully that the onions and mushrooms do not burn
Stir 2 cups of beef broth into the skillet and let simmer for 2-3 minutes along with the onions and mushrooms
In a glass bowl or large measuring cup, make a slurry of 1 cup of beef broth to 2 tbsp corn starch using a whisk to throughly incorporate
Add the slurry to the skillet stirring til gravy thickens (If gravy gets too thick add more beef broth to thin to consistency desired)
Carefully lay the meat patties back into the skillet and allow to simmer with the onion and mushroom gravy for about 3-6 minutes assuring the meat is thoroughly cooked
Add the last tbsp of butter to the gravy which will give the gravy a glossy finish making it irresistible. 🥰
Serve over mashed potatoes, noodles or rice OR on toasted Texas Toast