Preheat oven to 325F. Grease a 9 x 13 cake pan and set aside.
Remove excess liquid from zucchini shreds by pressing with a paper towel. Discard excess liquid.
In a large mixing bowl, combine brown sugar, oil, egg, milk and vanilla. Whisk until combined.
Add flour, cinnamon, baking soda and salt to liquid mixture. Stir to combine; Avoid over-stirring. Fold in zucchini.
In a small bowl, combine topping ingredients. Mixture should be coarse and crumbly.
Spread cake batter into prepared cake pan. Evenly sprinkle with cinnamon-sugar topping.
Bake for 45 minutes or until top bounces back when touched. Enjoy!