Preheat oven to 350 F. Arrange tortillas on the bottom of a greased 8 or 9-inch baking dish. Sprinkle with sausage.
Beat eggs, milk and cumin in medium bowl with a wire whisk until well blended. Stir in ½ cup cheese.
Pour egg mixture over corn tortillas.
Bake 30 minutes or until knife inserted in center comes out clean. Top with remaining ½ cut cheese. Bake until cheese is melted. Let stand 5 minutes before cutting into 4 squares to serve. Top with tomato and green onion, if desired.