Grease a 9x13 baking pan with butter and lightly flour.
Wash and shred the zucchini. Strain out any excess moisture.
In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
Using a standing mixer, beat the sugar, eggs, vegetable oil and vanilla until smooth.
Add the shredded zucchini, mix until combined.
On low speed, add the flour mixture and blend until fully combined. Do not over-mix!
Using a spatula, gently fold the blueberries into the cake batter.
Spread the batter into the prepared cake pan. Bake at 350º F for 40-50 minutes, or until a toothpick inserted into the center comes out clean (or with just a few crumbs).
Remove from the oven and allow the cake to cool completely before topping with the frosting.
Lemon Cream Cheese Frosting Instructions
Using a standing mixer, beat the cream cheese and butter until fluffy, 2-3 minutes.
Stir in the vanilla and lemon juice.
Gradually add the confectioners sugar. Beat on high speed until light and fluffy.