Step 2: Season and Shape the Patties
In a medium bowl, combine the ground beef and dry onion soup mix. Use clean hands to gently mix until the seasoning is evenly distributed throughout the meat — but do not overwork it, as this keeps the patties tender and juicy. Divide the seasoned beef mixture into 6 to 8 equal portions, depending on how large you like your patties. Shape each portion into a flat oval or round patty about half to three-quarters of an inch thick.
Step 3: Arrange in the Baking Dish
Arrange the raw ground beef patties in a single layer in the prepared glass baking dish, leaving just a little space between each one so the sauce can flow freely around them.
Step 4: Make and Pour the Sauce
In a separate bowl, whisk together the condensed cream of mushroom soup and the milk until smooth and pourable. Pour the creamy mushroom soup mixture evenly over the raw ground beef patties, making sure each patty is well coated and some sauce covers the bottom of the dish.
Step 5: Bake Covered
Cover the glass baking dish tightly with aluminum foil to keep the steam and moisture in while baking. This helps the patties cook through gently and stay perfectly tender. Bake in the preheated oven for 35 to 40 minutes, or until the patties are cooked through and no longer pink in the center — an instant-read thermometer should read 160°F (71°C) in the thickest part.
