Preheat oven to 375 degree F. Let piecrusts stand at room temperature for 15 minutes as directed on package. Meanwhile, beat 1 of the eggs with a fork; set aside. In a large bowl beat remaining 3 eggs with a fork; add cheeses, pepper, and basil, stirring well. Stir in spinach, bread crumbs, and tomatoes.
Line a 9-inch pie plate with 1 of the piecrusts; brush generously with some of the reserved egg. Spread cheese mixture evenly in crust. Top with second piecrust. Fold edges under to seal. Flute as desired. Brush with remaining reserved egg. Cut slits in top crust.
Bake in preheated oven for 45 minutes. If necessary to prevent overbrowning, cover edge with foil for the last 20 minutes of baking. Cool on a wire rack for 15 minutes before serving. Makes 8 servings.