This delicious snack cake was adapted, with permission, from Linda Carucci. Using a large sheet pan, it can feed a crowd. Consider taking this to a potluck or your local school's staff room- those teachers deserve a treat! It keeps well for several days, so don't hesitate to make it and enjoy with your own family all week.
Measure raisins into a 4-cup liquid measure. Add enough hot water, brandy, or other liqueur to cover raisins. Cover and set aside for 20 minutes to 24 hours.
Preheat oven to 350 degrees F (or 325 Convection). For a thin snack cake (to eat out of hand), butter an 11x16" rimmed baking sheet. If you prefer a denser cake (more suitable if you plan to serve the cake on a plate), butter a 9x13" baking pan; set aside.
In a large bowl, sift together flour, cinnamon, baking powder, baking soda, and salt; set aside.
In a medium bowl, beat eggs lightly. Add sugar and stir to combine. Whisk in olive oil, zucchini, and vanilla extract. Add egg mixture to dry ingredients and stir to combine. Strain raisins, reserving soaking liquor for another use. Add raisins and nuts to batter, and stir just to combine. Pour batter into prepared pan.
Bake until toothpick inserted in the center comes out clean, cake springs back when touched in the center, and cake begins to pull away from the side of the pan, 20 to 25 minutes for the 11x16" pan. If using a 9x13" pan, bake 50 to 55 minutes. Transfer cake (in the pan) to a cooling rack, and cool to room temperature.
With a zester or the small holes of a box grater, remove the zest from the lemons and finely chop 2 teaspoons of zest. Squeeze the lemons and measure out 1/4 cup of juice. Reserve any remaining zest and juice for another use.
In a medium bowl, combine lemon juice, olive oil, and lemon zest.
Sift powdered sugar into bowl and stir to combine. Cover icing with a piece of plastic wrap placed directly on the surface (to prevent a crust from forming), and set aside until cake is cool.
Leave cake in the pan and spread the top with icing. To prevent the icing from "cracking" when you cut the cake, score the cake into bars or squares before icing hardens. After serving, cover any remaining cake with plastic wrap and store at cool room temperature for up to 3 days, refrigerate for up to 1 week, or freeze for up to 1 month.