Whisk together dry ingredients in a large mixing bowl. In another bowl, whisk eggs, oil, sugar, and vanilla; add to dry ingredients with zucchini and nuts. Stir till well combined, then pour in greased 9x13" pan.
Bake at 350° for about 40 minutes or until toothpick comes out clean.
For frosting: Beat cream cheese and butter in a mixing bowl till smooth. Beat in powdered sugar and vanilla. I don't usually need to add any milk, but you might. Add as much as you need to get a creamy, spreadable consistency.