To make the homemade cream cheese frosting, mix vegan cream cheese, vegan butter, lemon juice, and vanilla in a mixing bowl until smooth. Add in powdered sugar and combine until smooth. Keep in the refrigerator until the cake is ready to frost.
Preheat oven to 350°. In a small bowl, make 4 flax eggs and set aside for 5-10 minutes.
In a large bowl, mix together flour, baking soda, cinnamon, nutmeg, and salt. In a medium bowl, whisk together raw and brown sugars, applesauce, and flax eggs. Add wet ingredients into dry ingredients, and stir in shredded zucchini and raisins (optional) until well-combined.
Pour batter into non-stick 9x9-inch pan. Bake for 30 minutes, or until toothpick comes out clean when inserted.
After cake has cooled completely on a wire rack, spread the cream cheese frosting onto the cake. Garnish with a handful of chopped walnuts, if desired. Enjoy!