Preheat the oven to 350 degrees F. Spray a cake pan (9x13) with non-stick cooking spray. Mix together milk with lemon juice. Set aside for 5 minutes. Beat eggs well, then add brown sugar, sugar, oil and beat together again. Add in vanilla, zucchini, carrots, cranberries and the milk and lemon mixture. Mix together well. Put the flour, cinnamon, baking soda, salt and nuts if you added any in another bowl. Mix them together and add the dry mixture with the wet mixture, mix together until just combined. Spoon the mixture into the oiled pan and sprinkle some cinnamon sugar mixture onto the top if desired. Bake for about 35-40 minutes or until wooden stick inserted into the middle comes out clean and the bars are not sticky in the middle. Turn off the oven but don't open the oven or take the pan out, just leave it in there for 5 minutes if you like the outside crispy. Don't over-bake, they become really dry and hard.