Preheat your oven to 350°F (175°C). Grease and flour an 8x8 inch baking pan.

In a medium bowl, whisk together flour, baking powder, baking soda, and salt until well combined.

In a large mixing bowl, cream together softened butter and granulated sugar until light and fluffy (2-3 minutes).

Add eggs one at a time, mixing well after each addition. Then mix in vanilla extract.

In a small bowl, whisk together yogurt and fresh lemon juice until smooth. Alternate adding this with dry mixture to large bowl.

Gently fold in grated zucchini and lemon zest.

Pour the batter into the prepared baking pan and spread it evenly.

Bake for 30-35 minutes. Check for doneness with a toothpick.

Allow to cool in the pan for 15-20 minutes, then transfer to a wire rack to cool completely.

Mix powdered sugar with milk or lemon juice until smooth. Drizzle glaze over cooled bars.