Preheat your oven to 350°F (175°C).

In a large mixing bowl, whisk together the eggs, brown sugar, oil, honey, and vanilla extract until well combined.

Gently fold in the shredded carrots and zucchini into your wet mixture, along with the optional chopped walnuts.

In a separate bowl, whisk together the all-purpose flour, baking powder, ground ginger, and baking soda.

Carefully add the dry mixture to your wet mixture, stirring gently until just combined.

Spread the batter evenly into an ungreased 13x9x2-inch baking pan.

Place the pan into the preheated oven and bake for approximately 25 minutes.

Once baked, remove the bars from the oven and allow them to cool in the pan on a wire rack for at least 1 hour.

While the bars cool, prepare the frosting by beating together the cream cheese, lemon zest, and optional sugar until fluffy.

Once your bars are completely cool, spread or pipe the lemon cream cheese frosting generously over the top.