1. 1. Preheat your oven to 350°F. Grease a 9×13-inch baking dish or line it with parchment paper for easy removal.

2. 2. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

3. 3. In a large bowl, beat the butter and sugar until light and fluffy.

4. 4. Mix in the eggs one at a time, then add the vanilla, yogurt (or sour cream), lemon juice, and lemon zest.

5. 5. Gently fold in the grated zucchini until it’s evenly combined.

6. 6. Add the dry ingredients to the wet mixture and stir until just combined. Pour the batter into the prepared baking dish and spread it evenly. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean.

7. 7. Allow the bars to cool completely. In a small bowl, whisk the powdered sugar with milk or lemon juice to create a smooth glaze. Drizzle the glaze over the cooled bars.

8. 8. Let the glaze set before slicing the bars into squares and serving.