Grease and lightly flour a 13x9x2-inch baking pan. Set aside.
In large mixing bowl, stir together flour, granulated sugar, cinnamon, baking soda, salt, and baking powder.
Add eggs, zucchini, oil, and the vanilla. Beat on low speed with an electric mixer until combined; beat 1 minute on medium speed. Stir in nuts, if you like. Pour batter into pan.
Bake in a 350 degree F oven 45 minutes or until a wooden toothpick inserted near the center comes out clean. Cool cake thoroughly in the pan on a wire rack.
Prepare Cream Cheese Frosting. Spread it over the cooled cake. Store in refrigerator. Makes 15 servings.