Heat oven to 450°F. Make pie crust as directed on box for One-Crust Baked Shell using 9-inch glass pie pan or 10-inch deep-dish pie pan. Bake 9 to 11 minutes or until light golden brown.
Reduce oven temperature to 350°F. In 10-inch skillet, cook ground beef over medium-high heat, stirring frequently, until beef is thoroughly cooked; drain. Stir in taco seasoning mix and salsa; heat to boiling. Reduce heat; simmer uncovered 5 minutes, stirring occasionally. Stir in mushrooms and half of the french fried onions. Spoon mixture into baked shell.
In small bowl, mix ricotta cheese, 1 cup of the taco-flavored cheese blend and the eggs. Spoon over beef mixture. Bake 25 to 35 minutes or until slightly puffed and set in center.
Remove pie from oven. Sprinkle remaining 1 cup cheese evenly over filling; sprinkle remaining french fried onions in center of filling.
Return to oven; bake 2 to 3 minutes longer or until cheese is melted. Sprinkle tomato around edge and in center of filling. Let pie stand 10 to 15 minutes before serving.