Combine cream cheese and butter in a 1-quart glass bowl. Microwave on high for 15-30 seconds, or until softened.
Stir to combine and add flour, cornflake crumbs and salt. Mix until the dough holds together. Press the mixture into a 9-inch glass pie pan. Microwave on high 4-5 minutes until crust appears dry, rotating twice.
For the filling, crumble the sausage in a glass bowl and add onion. Microwave on high for 4-5 minutes, or until the meat is set, stirring halfway through to break up the meat. Drain.
Stir in the mushrooms, olives and mustard. Spoon into the crust.
Beat eggs with the milk and pour over the meat. Microwave on high for 7 minutes, or until the egg is almost set, rotating the plate twice.
Top with the cheddar cheese and microwave on high for 1 minute, or until cheese is melted. Let stand for 10 minutes before serving.