Cook beef, mushrooms, garlic, salt, pepper, in skillet until juices have almost evaporated. Add a sprinkle of lawry's seasoning salt to season beef.
Stir in Worceteshire, then flour. Cook 1 minute and add beef broth and heavy cream. Simmer until gravy thickens. Pour into a baking dish and sprinkle peas over top and let cool.
In a bowl, combine hash browns, chives, 1 cup cheese, 1 tsp salt and mayo. Mix well and spread across top of beef layer. Spread remainder of cheese. and bake 45 minutes. I put broil on for a couple of minutes to get that good crispy top.