Place the ground beef into the casserole dish and spread it out so it covers the bottom of the dish and is about 2 or 2-1/2 inches thick. Press holes in the ground beef with your fingers.
Run the drained mushrooms and onion through your food processor at the same time so the onion and mushrooms pieces will be well mixed. Set aside.
Pour the Frenchís seasoning over the ground beef in the casserole, spreading it evenly so all the finger holes contain some of the seasoning. Then, spread the processed mushrooms and onion over the top.
Start at one end of the casserole dish and fold over the ground beef and start mixing everything together well using your hands. By the time you work your way to the other end of the dish, youíll have a well-blended meat mixture.
Hereís a little trick: Pat the mixture down so itís about 2-1/2 inches in thickness. Push your fingers down the sides of the meat and pull it away from the edge of the casserole all the way around. This gives you a little area for the small amount of grease that will run off during the cooking.
Roast in a preheated oven at 370 degrees for one hour. Remove from the oven and let set 10 minutes before slicing.
Youíll have a wonderful, tasty meatloaf that will knock your socks off. If you donít like to have your socks knocked off, just do what I do and sit down barefooted whenever youíre going to enjoy this meatloaf.